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8 tháng 12 2018

\(\left(2x-3\right)^2-\left(x+5\right)^2=0\)

\(\left(2x-3-x-5\right)\left(2x-3+x+5\right)=0\)

\(\left(x-8\right)\left(3x+2\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x-8=0\\3x+2=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=8\\x=-\frac{2}{3}\end{cases}}}\)

Vậy \(\orbr{\begin{cases}x=8\\x=-\frac{2}{3}\end{cases}}\)

4 tháng 12 2018

Câu e) là: 2x3 + 6x2 = x2 + 3x nhé

4 tháng 12 2018

a) \(2x\left(x-3\right)+5\left(x-3\right)=0\)

\(\Rightarrow\left(x-3\right)\left(2x+5\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-3=0\\2x+5=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=3\\2x=-5\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{5}{2}\end{matrix}\right.\)

b) \(\left(x^2-4\right)-\left(x-2\right)\left(3-2x\right)=0\)

\(\Rightarrow\left(x-2\right)\left(x+2\right)-\left(x-2\right)\left(3-2x\right)=0\)

\(\Rightarrow\left(x-2\right)\left(x+2-3+2x\right)=0\)

\(\Rightarrow\left(x-2\right)\left(3x-1\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-2=0\\3x-1=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=2\\3x=1\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{1}{3}\end{matrix}\right.\)

c) \(\left(2x+5\right)^2=\left(x+2\right)^2\)

\(\Rightarrow\left(2x+5\right)^2-\left(x+2\right)^2=0\)

\(\Rightarrow\left(2x+5-x-2\right)\left(2x+5+x+2\right)=0\)

\(\Rightarrow\left(x+3\right)\left(3x+7\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x+3=0\\3x+7=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=-3\\3x=-7\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=-3\\x=-\dfrac{7}{3}\end{matrix}\right.\)

d) \(x^2-5x+6=0\)

\(\Rightarrow x^2-2x-3x+6=0\)

\(\Rightarrow x\left(x-2\right)-3\left(x-2\right)=0\)

\(\Rightarrow\left(x-2\right)\left(x-3\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-2=0\\x-3=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=2\\x=3\end{matrix}\right.\)

e) \(2x^3+6x^2=x^2+3x\)

\(\Rightarrow2x^3+6x^2-x^2-3x=0\)

\(\Rightarrow2x^3+5x^2-3x=0\)

\(\Rightarrow x\left(2x^2+5x-3\right)=0\)

\(\Rightarrow2x^2+5x-3=0\)

\(\Rightarrow2x^2-6x+x-3=0\)

\(\Rightarrow2x\left(x-3\right)+\left(x-3\right)=0\)

\(\Rightarrow\left(x-3\right)\left(2x+1\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-3=0\\2x+1=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{1}{2}\end{matrix}\right.\)

f) \(\left(x^2-1\right)\left(x+2\right)-\left(x-2\right)\left(x^2+2x+4\right)-2x^2\)

\(\Rightarrow\left(x^2-1\right)\left(x+2\right)-\left(x^3-8\right)-2x^2=0\)

\(\Rightarrow x^3+2x^2-x+2-x^3+8-2x^2=0\)

\(\Rightarrow-x+10=0\)

\(\Rightarrow x=10\)

25 tháng 10 2019

\(2x^2-6x=0\)

\(\Rightarrow2x.\left(x-3\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}2x=0\\x-3=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0:2\\x=0+3\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=3\end{matrix}\right.\)

Vậy \(x\in\left\{0;3\right\}.\)

\(2x.\left(x+2\right)-3.\left(x+2\right)=0\)

\(\Rightarrow\left(x+2\right).\left(2x-3\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x+2=0\\2x-3=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0-2\\2x=3\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-2\\x=3:2\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-2\\x=\frac{3}{2}\end{matrix}\right.\)

Vậy \(x\in\left\{-2;\frac{3}{2}\right\}.\)

\(x^3-16x=0\)

\(\Rightarrow x.\left(x^2-16\right)=0\)

\(\Rightarrow x.\left(x^2-4^2\right)=0\)

\(\Rightarrow x.\left(x-4\right).\left(x+4\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\x-4=0\\x+4=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=0+4\\x=0-4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=4\\x=-4\end{matrix}\right.\)

Vậy \(x\in\left\{0;4;-4\right\}.\)

Chúc bạn học tốt!

4 tháng 9 2015

bn vào câu hỏi tương tự tham khảo cách lm nhé

4 tháng 9 2015

vào câu hỏi tương tự

28 tháng 7 2016

a)(2x-3)2=(x+5)2

=>4x2-12x+9=x2+10x+25

=>3x2-22x-16=0

=>3x2+2x-24x-16=0

=>x(3x+2)-8(3x+2)=0

=>(x-8)(3x+2)=0

=>x=8 hoặc x=-2/3

b)X2.(x-1)-4x2+8x-4=0

=>x2(x-1)-4x2+4x+4x-4=0

=>x2(x-1)-4x(x-1)-4(x-1)=0

=>x2(x-1)-(4x-4)(x-1)=0

=>(x2-4x+4)(x-1)=0

=>(x-2)2(x-1)=0

=>x=2 hoặc x=1

c) 4x2- 25 - (2x- 5) . ( 2x+7)=0

=>4x2-25-(4x2+14x-10x-35)=0

=>4x2-25-4x2-14x+10x+35=0

=>-4x+10=0

=>-4x=-10 <=>x=5/2

d) x3+27+(x+3).(x-9)=0

=>x3+33+(x+3)(x-9)=0

=>(x+3)(x2-3x+9)+(x+3)(x-9)=0

=>(x2-3x+9+x-9)(x+3)=0

=>(x2-2x)(x+3)=0

=>x(x-2)(x+3)=0

=>x=0 hoặc x=2 hoặc x=-3

e) (x-2).(x+5)- x2+4=0

=>(x-2)(x+5)-(x-2)(x+2)=0

=>(x-2)(x+5-x-2)=0

=>3(x-2)=0 <=>x=2

28 tháng 7 2016

Sau khi khai triển hằng đẳng thức và thực hiện chuyển vế bạn sẽ đk kết quả như này!(\(\left(2x-3\right)^2=\left(x+5\right)^2=3x^2-22x-14\)

5 tháng 12 2017

1)⇔x2+1x-3x+3=0

⇔x(x+1)-3(x+1)=0

⇔(x+1)(x-3)=0

⇔x+1=0 hoặc x-3=0

⇔x=-1 hoặc x=3

5 tháng 12 2017

4)⇔x(1+5x)=0

⇔x=0 hoặc 1+5x=0

⇔x=0 hoặc 5x=-1

⇔x=0 hoặc x=-0.2

11 tháng 4 2020

b)

\(2x\cdot\left(2x-3\right)=\left(3-2x\right)\cdot\left(2-5x\right)\\ \Leftrightarrow-2x\cdot\left(3-2x\right)-\left(3-2x\right)\cdot\left(2-5x\right)=0\\ \Leftrightarrow\left(3-2x\right)\cdot\left(-2x-2+5x\right)=0\\ \Leftrightarrow\left(3-2x\right)\cdot\left(3x-2\right)=0\\ \Rightarrow\left[{}\begin{matrix}3-2x=0\\3x-2=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=\frac{3}{2}\\x=\frac{2}{3}\end{matrix}\right.\)

c)

\(2x^3+6x^2=x^2+3x\\ \Leftrightarrow2x^3+6x^2-x^2-3x=0\\ \Leftrightarrow x\cdot\left(2x^2+6x-x-3\right)=0\\ \Leftrightarrow x\cdot\left(-3+6x-x+2x^2\right)=0\\ \Leftrightarrow x\cdot\left[-3\cdot\left(1-2x\right)-x\cdot\left(1-2x\right)\right]=0\\ \Leftrightarrow x\cdot\left(-3-x\right)\cdot\left(1-2x\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=0\\-3-x=0\\1-2x=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=0\\x=-3\\x=\frac{1}{2}\end{matrix}\right.\)

d)

\(x^2-5x+6=0\\ \Leftrightarrow x^2-3x-2x+6=0\\ \Leftrightarrow6-2x-3x+x^2=0\\ \Leftrightarrow2\cdot\left(3-x\right)-x\cdot\left(3-x\right)=0\\ \Leftrightarrow\left(2-x\right)\cdot\left(3-x\right)=0\\ \Rightarrow\left[{}\begin{matrix}2-x=0\\3-x=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=2\\x=3\end{matrix}\right.\)

e)

\(\left(2x+5\right)^2=\left(x+2\right)^2\\ \Leftrightarrow\left(2x+5\right)^2-\left(x+2\right)^2=0\\ \Leftrightarrow\left(2x+5+x+2\right)\cdot\left(2x+5-x-2\right)=0\\ \Leftrightarrow\left(3x+7\right)\cdot\left(x+3\right)=0\\ \Rightarrow\left[{}\begin{matrix}3x+7=0\\x+3=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=-\frac{7}{3}\\x=-3\end{matrix}\right.\)

11 tháng 4 2020

a) \(\left(x+3\right)\left(x+5\right)+\left(x+3\right)\left(3x-4\right)=0\)

\(\left(x+3\right)\left(x+5+1+3x-4\right)=0\)

\(\left[{}\begin{matrix}x+3=0\\x+3x=2\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-3\\x=\frac{1}{2}\end{matrix}\right.\)

Mk đang hok zoom sorry nha!!!

12 tháng 10 2020

a) 2x (x-5) -(x2-10x +25)=0

\(\Leftrightarrow\)2x(x-5)-(x-5)2=0

\(\Leftrightarrow\)(x-5)(2x-x+5)=0

\(\Leftrightarrow\)(x-5)(x+5)=0

\(\Leftrightarrow\)\(\left[{}\begin{matrix}x-5=0\\x+5=0\end{matrix}\right.\)

\(\Leftrightarrow\)\(\left[{}\begin{matrix}x=5\\x=-5\end{matrix}\right.\)

b) x2 - 9 +3x(x+3) = 0

\(\Leftrightarrow\)(x2 - 9) +3x(x+3) =0

\(\Leftrightarrow\)(x-3)(x+3)+3x(x+3)=0

\(\Leftrightarrow\)(x+3)(x-3+3x)=0

\(\Leftrightarrow\)(x+3)(4x-3)=0

\(\Leftrightarrow\)\(\left[{}\begin{matrix}x+3=0\\4x-3=0\end{matrix}\right.\)

\(\Leftrightarrow\)\(\left[{}\begin{matrix}x=-3\\4x=3\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=\frac{3}{4}\end{matrix}\right.\)

c) x3 - 16x = 0

\(\Leftrightarrow\)x(x2-16)=0

\(\Leftrightarrow\)x(x-4)(x+4)=0

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x-4=0\\x+4=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\\x=-4\end{matrix}\right.\)

d) (2x+3)(x-2) - (x2 -4x+4) = 0

\(\Leftrightarrow\)(2x+3)(x-2) -(x-2)2=0

\(\Leftrightarrow\)(x-2)(2x+3-x+2)=0

\(\Leftrightarrow\)(x-2)(x+5)=0

\(\Leftrightarrow\left[{}\begin{matrix}x-2=0\\x+5=0\end{matrix}\right.\)

\(\Leftrightarrow\)\(\left[{}\begin{matrix}x=2\\x=-5\end{matrix}\right.\)

e) 9x2 -(x2 -2x +1)=0

\(\Leftrightarrow\)(3x)2-(x-1)2=0

\(\Leftrightarrow\)(3x-x+1)(3x+x-1)=0

\(\Leftrightarrow\)(2x+1)(4x-1)=0

\(\Leftrightarrow\)\(\left[{}\begin{matrix}2x+1=0\\4x-1=0\end{matrix}\right.\)

\(\Leftrightarrow\)\(\left[{}\begin{matrix}2x=-1\\4x=1\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{-1}{2}\\x=\frac{1}{4}\end{matrix}\right.\)

f)x3-4x2 -9x +36 = 0

\(\Leftrightarrow\)(x3-9x)-(4x2-36)=0

\(\Leftrightarrow\)x(x2-9)-4(x2-9)=0

\(\Leftrightarrow\)(x-4)(x2-9)=0

\(\Leftrightarrow\)(x-4)(x-3)(x+3)=0

\(\Leftrightarrow\left[{}\begin{matrix}x-4=0\\x-3=0\\x+3=0\end{matrix}\right.\)

\(\Leftrightarrow\)\(\left[{}\begin{matrix}x=4\\x=3\\x=-3\end{matrix}\right.\)

g) 3x - 6 = (x-1).(x-2)

\(\Leftrightarrow\)3(x-2)=(x-1)(x-2)

\(\Leftrightarrow\)x-1=3

\(\Leftrightarrow\)x=4

i) (x-2).(x+2) +(2x+1)2 =-5x.(x-3) =5 (?? đề sao vậy ??)

k) x2 -1 = (x-1).(2x+3)

\(\Leftrightarrow\)(x-1)(x+1)=(x-1)(2x+3)

\(\Leftrightarrow\)x+1=2x+3

\(\Leftrightarrow\)x-2x=3-1

\(\Leftrightarrow\)-x=2

\(\Leftrightarrow\)x=-2

l) (2x-1)2 +(x+3).(x-3) -5x(x-2)=6

\(\Leftrightarrow\)4x2-4x+1+x2-9-5x2+10x=6

\(\Leftrightarrow\)6x-8=6

\(\Leftrightarrow\)6x=14

\(\Leftrightarrow\)x=\(\frac{7}{3}\)

31 tháng 12 2017

a. \(2x\left(x+5\right)-x\left(3+2x\right)=26\Leftrightarrow2x^2+10x-3x-2x^2=26\Leftrightarrow7x=26\Leftrightarrow x=\dfrac{26}{7}\)

Vậy \(x=\dfrac{26}{7}\)

b. \(5x\left(x-1\right)=x-1\Leftrightarrow5x\left(x-1\right)-\left(x-1\right)=0\Leftrightarrow\left(x-1\right)\left(5x-1\right)=0\Leftrightarrow\left[{}\begin{matrix}x-1=0\\5x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\5x=1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=\dfrac{1}{5}\end{matrix}\right.\)

Vậy \(\left[{}\begin{matrix}x=1\\x=\dfrac{1}{5}\end{matrix}\right.\)

c. \(2\left(x+5\right)-x^2-5x=0\Leftrightarrow2\left(x+5\right)-x\left(x+5\right)=0\Leftrightarrow\left(x+5\right)\left(2-x\right)=0\Leftrightarrow\left[{}\begin{matrix}x+5=0\\2-x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-5\\x=2\end{matrix}\right.\)

Vậy \(\left[{}\begin{matrix}x=-5\\x=2\end{matrix}\right.\)

d. \(\left(2x-3\right)^2-\left(x+5\right)^2=0\Leftrightarrow\left(2x-3-x-5\right)\left(2x-3+x+5\right)=0\Leftrightarrow\left(x-8\right)\left(3x+2\right)=0\Leftrightarrow\left[{}\begin{matrix}x-8=0\\3x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=8\\3x=-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=8\\x=-\dfrac{2}{3}\end{matrix}\right.\)

Vậy \(\left[{}\begin{matrix}x=8\\x=-\dfrac{2}{3}\end{matrix}\right.\)

e. \(3x^3-48x=0\Leftrightarrow3x\left(x^2-16\right)=0\Leftrightarrow\left[{}\begin{matrix}3x=0\\x^2-16=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x^2=16\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\pm4\end{matrix}\right.\)

Vậy \(\left[{}\begin{matrix}x=0\\x=\pm4\end{matrix}\right.\)

f. \(x^3+x^2-4x=4\Leftrightarrow x^3+x^2-4x-4=0\Leftrightarrow\left(x^2-4x+4\right)+\left(x^3-8\right)=0\Leftrightarrow\left(x-2\right)^2+\left(x-2\right)\left(x^2+2x+4\right)=0\Leftrightarrow\left(x-2\right)\left(x-2+x^2+2x+4\right)=0\left(x-2\right)\left(x^2+3x+2\right)=0\Leftrightarrow\left(x-2\right)\left(x^2+x+2x+2\right)=0\Leftrightarrow\left(x-2\right)\left[x\left(x+1\right)+2\left(x+1\right)\right]=0\Leftrightarrow\left(x-2\right)\left(x+1\right)\left(x+2\right)=0\Leftrightarrow\left[{}\begin{matrix}x-2=0\\x+1=0\\x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-1\\x=-2\end{matrix}\right.\)

Vậy \(\left[{}\begin{matrix}x=-1\\x=\pm2\end{matrix}\right.\)

g. \(\left(x-1\right)\left(2x+3\right)-x\left(x-1\right)=0\Leftrightarrow\left(x-1\right)\left(2x+3-x\right)=0\Leftrightarrow\left(x-1\right)\left(x+3\right)=0\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-3\end{matrix}\right.\)

Vậy \(\left[{}\begin{matrix}x=1\\x=-3\end{matrix}\right.\)

h. \(x^2-4x+8=2x-1\Leftrightarrow x^2-4x+8-2x+1=0\Leftrightarrow x^2-6x+9=0\Leftrightarrow\left(x-3\right)^2=0\Leftrightarrow x-3=0\Leftrightarrow x=3\)

Vậy \(x=3\)

__________________________Chúc bạn học tốt____________________________

1 tháng 1 2018

Thankshihi

3 tháng 10 2016

de qua

6 tháng 8 2018

x.(2.x-1)+1/3-2/3.x=0

4 tháng 12 2018

Bài 1:

a) \(x^2+9y^2-y^4-6xy\)

\(=\left(x^2-6xy+9y^2\right)-y^4\)

\(=\left[x^2-2.x.3y+\left(3y\right)^2\right]-\left(y^2\right)^2\)

\(=\left(x-3y\right)^2-\left(y^2\right)^2\)

\(=\left(x-3y-y^2\right)\left(x-3y+y^2\right)\)

b) \(2x^2-x-28\)

\(=2x^2-8x+7x-28\)

\(=2x\left(x-4\right)+7\left(x-4\right)\)

\(=\left(x-4\right)\left(2x+7\right)\)

Bài 2:

a) \(2x\left(x^2-2x+3\right)-2x^3\)

\(=2x\left(x^2-2x+3-x^2\right)\)

\(=2x\left(3-2x\right)\)

b) \(2x\left(x-3\right)-\left(x+5\right)\left(2x-1\right)\)

\(=\left(2x^2-6x\right)-\left(2x^2+9x-5\right)\)

\(=2x^2-6x-2x^2-9x+5\)

\(=-15x+5\)

\(=-5\left(3x-1\right)\)

c) \(\left(5-x\right)^2+\left(x+5\right)^2-\left(2x+10\right)\left(x-5\right)\)

\(=\left(x-5\right)^2-2\left(x+5\right)\left(x-5\right)+\left(x+5\right)^2\)

\(=\left[\left(x-5\right)-\left(x+5\right)\right]^2\)

\(=\left(x-5-x-5\right)^2\)

\(=\left(-10\right)^2=100\)

Bài 3:

a) \(x-2=\left(x-2\right)^2\)

\(\Rightarrow\left(x-2\right)-\left(x-2\right)^2=0\)

\(\Rightarrow\left(x-2\right)\left(1-x+2\right)=0\)

\(\Rightarrow\left(x-2\right)\left(3-x\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-2=0\\3-x=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=2\\x=3\end{matrix}\right.\)

b) \(\left(-3x+9\right)x^2-7x+21=0\)

\(\Rightarrow-3\left(x-3\right)x^2-7\left(x-3\right)=0\)

\(\Rightarrow\left(x-3\right)\left(-3x^2-7\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-3=0\\-3x^2-7=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=3\\x^2=-\dfrac{7}{3}\end{matrix}\right.\)

Mà x2 > 0 hoặc x2 = 0 với mọi x

=> x2 = -7/3 không thỏa mãn

=> x= 3

4 tháng 12 2018

Phân tích đa thức

a, x^2+9y^2-y^4-6xy

=(x^2-6xy+9y^2)-y^4

=(x-3y)^2-y^4

=(x-3y-y^2)(x-3y+y^2)

b, 2x^2-x-28

=(2x^2-8x)+(7x-28)

=2x(x-4)+7(x-4)

=(x-4)(2x+7)

Rút gọn

a,2x(x^2-2x+3)-2x^3

=2x(x^2-2x+3-x^2)

=2x(-2x+3)

b,2x(x-3)-(x+5)(2x-1)

=2x^2-6x-2x^2-9x+5

=-15x+5

=-5(3x-1)

c,(5-x)^2+(x+5)^2-(2x+10)(x-5)

Ta có:(5-x)^2=(x-5)^2

=(x-5)^2-2(x+5)(x-5)+(x+5)^2

=(x-5-x-5)^2

=100

Tìm x

a,x-2=(x-2)^2=0

=>x-2=0=>x=2

b,(-3x+9)x^2-7x+21=0

=>-3(x-3)x^2-7(x-3)=0

=>(x-3)(-3x^2-7)=0

=>\(\left[{}\begin{matrix}x-3=0=>x=3\\-3x^2-7=0=>x=\sqrt{\dfrac{-7}{3}}\end{matrix}\right.\)