Tìm x biết x2 < x
Tìm x, biết:
a) x 2 (x - 5) + 5 - x = 0; b) 3 x 4 - 9 x 3 = -9 x 2 + 27x;
c) x 2 (x + 8) + x 2 = -8x; d) (x + 3)( x 2 -3x + 5) = x 2 + 3x.
Tìm x, biết: ( x – 4 ) ( x 2 + 4 x + 16 ) – x ( x 2 – 6 ) = 2
b) (x – 4). (x2 + 4x + 16) – x. (x2 - 6) = 2
⇔ x3 + 4x2 + 16x – 4x2 – 16x – 64 – (x3 - 6x ) – 2= 0
⇔ x3 + 4x2 + 16x – 4x2 – 16x – 64 – x3 + 6x – 2= 0
⇔ 6x – 66 =0
⇔ 6x = 66
⇔ x = 66 : 6
⇔ x = 11
Vậy x = 11
Tìm x, biết
a) (x2+4)-(x+1)(x-1)=16
b) X2 -x-12=0
b: \(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-3\end{matrix}\right.\)
Tìm x biết:
a) ( x – 1 ) 3 + ( 2 – x ) ( 4 + 2 x + x 2 ) + 3x(x + 2) = 16;
b) (x + 2)( x 2 – 2x + 4) – x( x 2 – 2) = 15.
a) Rút gọn được VT = 9x + 7. Từ đó tìm được x = 1.
b) Rút gọn được VT = 2x + 8. Từ đó tìm được x = 7 2 .
Tìm x, biết
(x - 2)(x2 + 2x + 4) + 2(x2 - 4) - 5(x - 2) = 0
(x - 2)(x2 + 2x + 4) + 2(x2 - 4) - 5(x - 2) = 0
(x - 2)(x + 2)2 + 2(x - 2)(x+2) - 5(x - 2) = 0
(x - 2)[(x+2)2 + 2(x+2) - 5]= 0
(x - 2)[(x + 2)2 + 2(x + 2) + 1 - 6] = 0
( x - 2)[(x + 2 + 1)2 - 6] = 0
(x - 2)[(x + 3)2 - 6] = 0
(x - 2)(x + 3 - \(\sqrt{6}\))(x + 3 + \(\sqrt{6}\)) = 0
TH1. x - 2 = 0 <=> x = 2
TH2. x + 3 - \(\sqrt{6}\) = 0 <=> x = \(\sqrt{6}-3\)
TH3. x + 3 + \(\sqrt{6}\) = 0 <=> x = \(-\sqrt{6}-3\)
S = {2; \(\sqrt{6}-3\); \(-\sqrt{6}-3\)}
Tìm x biết: x thuộc Z và ( x 2 - 5 ) . ( x 2 - 24 ) < 0
Tìm x, biết:
a) x 2 (x + 5)- 9x = 45; b) 9(5-x) + x 2 -l0x = -25.
ai biết 45 : (x – 4) = 9 bằng bao nhiêu ko
Tìm x biết rằng:
a) ( x 2 + 2x + 4)(2 - x) + x(x - 3)(x + 4) - x 2 + 24 = 0;
b) x 2 + 3 ( 5 − 6 x ) + ( 12 x − 2 ) x 4 + 3 = 0 .
Bài 5. Tìm x , biết rằng: a) x(x + 5)(x – 5) – (x + 2)(x2 – 2x + 4) = 3
b) (x – 3)3 – (x – 3)(x2 + 3x + 9) + 9(x + 1)2 = 15
c) (x+5)(x2 –5x +25) – (x – 7) = x3
d) (x+2)(x2 – 2x + 4) – x(x2 + 2) = 4
`a) x(x + 5)(x – 5) – (x + 2)(x^2 – 2x + 4) = 3`
`<=>x(x^2-25)-(x^3-8)=3`
`<=>x^3-25x-x^3+8=3`
`<=>-25x=-5`
`<=>x=1/5`
`b) (x – 3)^3 – (x – 3)(x^2 + 3x + 9) + 9(x + 1)^2 = 15`
`<=>x^3-9x^2+27x-27-(x^3-27)+9(x^2+2x+1)=15`
`<=>-9x^2+27x+9x^2+18x+9=15`
`<=>45x+9=15`
`<=>45x=6`
`<=>x=6/45=2/15`
`c) (x+5)(x^2 –5x +25) – (x – 7) = x^3`
`<=>x^3-125-x+7=x^3`
`<=>x^3-x-118=x^3`
`<=>-x-118=0`
`<=>-x=118<=>x=-118`
`d) (x+2)(x^2 – 2x + 4) – x(x^2 + 2) = 4 `
`<=>x^3+8-x^3-2x=4`
`<=>8-2x=4`
`<=>2x=4<=>x=2`
Tìm x biết :
a) (x+2)2+(x-3)2 = 2x(x+7)
b) (x+3)(x2-3x+9) = x(x2+4)-1
a, (x+2)2+(x-3)2=2x(x+7)
x.2+2.2+x.2+(-3).2-2x=8
2x+4+2x-6-2x=8
(2x+2x)+(4-6)=8
4x-2=8
4x=8+2
4x=10
X=10:4
X=5/2
a) (x+2)2+(x-3)2 = 2x(x+7)
⇒x2+4x+4+x2-6x+9=2x2+14x
⇒x2+4x+4+x2-6x+9-2x2-14x=0
⇒ -16x+13=0
⇒ x=\(\dfrac{13}{16}\)
b) (x+3)(x2-3x+9) = x(x2+4)-1
⇒x(x2-3x+9)+3(x2-3x+9)=x3+4x-1
⇒x3-3x2+9x+3x2-9x+27-x3-4x+1=0
⇒-4x+28=0
⇒x=7
a: Ta có: \(\left(x+2\right)^2+\left(x-3\right)^2=2x\left(x+7\right)\)
\(\Leftrightarrow x^2+4x+4+x^2-6x+9-2x^2-14x=0\)
\(\Leftrightarrow-16x=-13\)
hay \(x=\dfrac{13}{16}\)
b: Ta có: \(\left(x+3\right)\left(x^2-3x+9\right)=x\left(x^2+4\right)-1\)
\(\Leftrightarrow x^3+27-x^3-4x=-1\)
\(\Leftrightarrow-4x=-28\)
hay x=7