Tìm x biết |5 -3x2 | = 358
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\left(x+5\right).6-7=29\)
\(\Rightarrow\left(x+5\right).6=29+7\)
\(\Rightarrow\left(x+5\right).6=36\)
\(\Rightarrow\left(x+5\right)=36:6=6\)
\(\Rightarrow x=6-5=1\)
b) \(5x-3x=12-3.2\)
\(\Rightarrow2x=6\Rightarrow x=6:2=3\)
c) \(\dfrac{1}{4}.3< x< \dfrac{51}{50}.4\)
\(\Rightarrow\dfrac{3}{4}< x< \dfrac{102}{25}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
1794:x+358=404
1794:x=404-358
1794:x=46
x=1794:46
x=39
nhớ tk m nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(\left(x+5\right)^2-\left(x-5\right)^2-2x+1=0\)
=>\(x^2+10x+25-\left(x^2-10x+25\right)-2x+1=0\)
=>\(x^2+8x+26-x^2+10x-25=0\)
=>18x+1=0
=>\(x=-\dfrac{1}{18}\)
b: \(\left(2x-7\right)^2-\left(x+3\right)^2=3x^2+6\)
=>\(4x^2-28x+49-\left(x^2+6x+9\right)-3x^2-6=0\)
=>\(x^2-28x+43-x^2-6x-9=0\)
=>34-34x=0
=>34x=34
=>x=1
c: \(\left(3x+2\right)^2-9\left(x-5\right)\left(x+5\right)=225-5x\)
=>\(9x^2+12x+4-9\left(x^2-25\right)-225+5x=0\)
=>\(9x^2+17x+4-225-9x^2+225=0\)
=>17x+4=0
=>x=-4/17
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,x^2=5\Leftrightarrow x=\pm\sqrt{5}\)
Vậy \(S=\left\{\pm\sqrt{5}\right\}\)
\(b,3x^2-12=0\Leftrightarrow3x^2=12\Leftrightarrow x^2=4\Leftrightarrow x=\pm2\)
Vậy \(S=\left\{\pm2\right\}\)
\(c,4x^2-3=-9\)
\(\Leftrightarrow4x^2=-6\)
\(\Leftrightarrow x^2=-\dfrac{3}{2}\) (loại)
Vậy pt vô nghiệm.
\(d,5x^2-3=-3\)
\(\Leftrightarrow5x^2=0\)
\(\Leftrightarrow x=0\)
Vậy \(S=\left\{0\right\}\)
a)
`x^2 =5`
`=>\(\left[{}\begin{matrix}x=\sqrt{5}\\x=-\sqrt{5}\end{matrix}\right.\)
b)
`3x^2 -12=0`
`<=>3x^2 =12`
`<=>x^2 =4`
\(< =>\left[{}\begin{matrix}x=2\\x=-2\end{matrix}\right.\)
c)
`4x^2 -3=-9`
`<=>4x^2 =-6`
`<=>x^2 =-3/2` (vô lí vì `x>=0AA x` )
d)
`5x^2 -3=3`
`<=>5x^2 =0`
`<=>x^2 =0`
`<=>x=0`
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có: f(x) + h(x) = g(x)
Suy ra: h(x) = g(x) – f(x) = (x4 – x3 + x2 + 5) – (x4 – 3x2 + x – 1)
= x4 – x3 + x2 + 5 – x4 + 3x2 – x + 1
= ( x4 – x4) – x3 + (x2 + 3x2 ) – x + (5+ 1)
= -x3 + 4x2 – x + 6
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có: f(x) – h(x) = g(x)
Suy ra: h(x) = f(x) – g(x) = (x4 – 3x2 + x – 1) – (x4 – x3 + x2 + 5)
= x4 – 3x2 + x – 1 – x4 + x3 – x2 – 5
= (x4 – x4) + x3 – (3x2 + x2) + x - (1+ 5)
= x3 – 4x2 + x – 6