Question

tìm x biết 

( x² + 2x + 4 ) * ( 2 - x ) +  x( x - 3 ) * ( x + 4 ) - x² + 24 = 0

Answer 1

\(=>2^3-x^3+\left(x^2-3x\right)\left(x+4\right)-x^2+24=0\)

\(=>8-x^3+x^3+x^2-12x-x^2+24=0\)

\(=>-12x=-16=>x=\frac{4}{3}\)

Vậy \(x=\frac{4}{3}\)

Answer 2

\(\left(x^2+2x+4\right)\left(2-x\right)+x\left(x-3\right)\left(x+4\right)-x^2+24=0\)

\(\Leftrightarrow2x^2-x^3+4x-2x^2+8-4x+\left(x^2-3x\right)\left(x+4\right)-x^2+24=0\)

\(\Leftrightarrow2x^2-x^3+4x-2x^2+8-4x+x^3+4x^2-3x^2-12x-x^2+24=0\)

\(\Leftrightarrow-12x+8+24=0\)

\(\Leftrightarrow-12x+32=0\)

\(\Leftrightarrow-12x=-32\)

\(\Leftrightarrow x=\frac{8}{3}\)

Answer 3

á , mình sai rồi -12x=-32 nha

Answer 4

(x² + 2x + 4)(2 - x) + x(x - 3)(x + 4) - x² + 24 = 0

<=> (x² + 2x + 4)(2 - x) + x(x - 3)(x + 4) - x² = 0 - 24

<=> (x² + 2x + 4)(2 - x) + x(x - 3)(x + 4) - x² = -24

<=> (x² + 2x + 4)(2 - x) + x(x² + x - 12) = -24

<=> x².2 + x².(-x) + 2x.2 + 2x.(-x) + 4.2 + 4.(-x) + x.x² + x.x + x.(-12) = -24

<=> 2x² - x³ + 4x - 2x² + 8 - 4x + x³ + x² - 12x = -24

<=> -12x + 8 = -24

<=> -12x = -24 - 8

<=> -12x = -32

<=> x = 8/3

=> x = 8/3