0,36x740-72/20x4+36x3
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\(9x^4+36x^3+29x^2-14x\)
\(=x\left(9x^3+36x^2+29x-14\right)\)
\(=x\left(9x^3+18x^2+18x^2+36x-7x-14\right)\)
\(=x\left[9x^2\left(x+2\right)+18x\left(x+2\right)-7\left(x+2\right)\right]\)
\(=x\left(x+2\right)\left(9x^2+18x-7\right)\)
\(=x\left(x+2\right)\left(9x^2-3x+21x-7\right)\)
\(=x\left(x+2\right)\left[3x\left(3x-1\right)+7\left(3x-1\right)\right]\)
\(=x\left(x+2\right)\left(3x+7\right)\left(3x-1\right)\)
ta có: 20=21-1=x-1
B=x6-20x5-20x4-20x3-20x2-20x+3
= x6-(x-1)x5-(x-1)x4-(x-1)x3-(x-1)x2-(x-1)x+3
=x6-x6+x5-x5+x4-x4+x3-x3+x2-x2+x+3
=x+3
=21+3
=24
(x:10)x5=1000-80
(x:10)x5=920
(x:10) =920 : 5
(x:10) =184
x =184 x 10
x =1840
x=21
=>x-1=20
B=x^6-x^5(x-1)-x^4(x-1)-...-x(x-1)+3
=x^6-x^6+x^5-x^5+x^5-...-x^2+x+3
=x+3
=21+3=24
a , Y = \(\dfrac{20\times4}{35\times5}\)
Y = \(\dfrac{4\times4\times5}{35\times5}\)
Y = \(\dfrac{16}{35}\)
b, \(\dfrac{5\times7}{21\times15}\) = \(\dfrac{y}{9}\)
\(\dfrac{5\times7}{5\times3\times3\times7}\) = \(\dfrac{y}{9}\)
\(\dfrac{1}{9}\) = \(\dfrac{y}{9}\)
y = 1
A) Y = \(\dfrac{80}{175}=\dfrac{16}{35}\)
vậy Y ≈ 0,5 ( phần a thì mình chưa rõ nhé, bn có thể viết phân số/ hoặc hỏi thầy cô xem tnao nha )
B) Y/9 = \(\dfrac{35}{315}=\dfrac{1}{9}\)
vậy Y = 1
\(x^6+2x^3+1=0\)
\(\Leftrightarrow\left(x^3\right)^2+2x^3+1=0\)
\(\Leftrightarrow\left(x^3+1\right)^2=0\)
\(\Leftrightarrow x^3=\left(-1\right)^3\)
\(\Leftrightarrow x=-1\)
___________
\(x\left(x-5\right)=4x-20\)
\(\Leftrightarrow x\left(x-5\right)-4\left(x-5\right)=0\)
\(\Leftrightarrow\left(x-5\right)\left(x-4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=5\end{matrix}\right.\)
_____________
\(x^4-2x^2=8-4x^2\)
\(\Leftrightarrow x^2\left(x^2-2\right)+\left(4x^2-8\right)=0\)
\(\Leftrightarrow x^2\left(x^2-2\right)+4\left(x^2-2\right)=0\)
\(\Leftrightarrow\left(x^2-2\right)\left(x^2+4\right)=0\)
\(\Leftrightarrow x^2=2\)
\(\Leftrightarrow x=\pm\sqrt{2}\)
_______________
\(\left(x^3-x^2\right)-4x^2+8x-4\)
\(\Leftrightarrow x^2\left(x-1\right)-4\left(x^2-2x+1\right)=0\)
\(\Leftrightarrow x^2\left(x-1\right)-4\left(x-1\right)^2=0\)
\(\Leftrightarrow\left(x-1\right)\left(x^2-4x+4\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x-2\right)^2=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)
a) Ta có: \(36x^3-4x=0\)
\(\Leftrightarrow4x\left(9x^2-1\right)=0\)
\(\Leftrightarrow x\left(3x-1\right)\left(3x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{3}\\x=\dfrac{-1}{3}\end{matrix}\right.\)
b) Ta có: \(3x\left(x-2\right)+x-2=0\)
\(\Leftrightarrow\left(x-2\right)\left(3x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{-1}{3}\end{matrix}\right.\)
a) 20x4+20x3+20x3
= 20 x ( 4+3 + 3)
= 20 x10
= 200
b) (6x9-54)x(25 +26+27+.........41+42)
= 0 x (25 +26+27+.........41+42)
= 0
20x4+20x3+20x3
= 20 x ( 4+3 + 3)
= 20 x10
= 200
b) (6x9-54)x(25 +26+27+.........41+42)
= 0 x (25 +26+27+.........41+42)
= 0
\(0,36\times740-\dfrac{72}{20}\times4+36\times3\)
\(=0,36\times740-0,36\times10\times4-0,36\times100\times3\)
\(=0,36\times740-0,36\times40+0,36\times300\)
\(=0,36\times\left(740-40+300\right)\)
\(=0,36\times1000\)
\(=360\)
0,36 x 740 - \(\dfrac{72}{20}\) x 4 + 36 x 3
= 3,6 x 74 - 3,6 x 4 + 3,6 x 30
= 3,6 x ( 74 - 4 + 30)
= 3,6 x 100
= 360