Question

[pé lầyy]

giải pt 

a 2(x+3)(x-4)=(2x-1)(x+2)-27

b (3x+2)(x-1)-3(x+1)(x-2)=4

c (x+2)(x^2 -2x+4)-x(x-3)(x+3)=26

d (3x+2)(3x-2)-(3x-4)^2=28

e 5(x+3)^2-5(x-4)(x+8)=3x

f 2x(x+2)^2-8x^2=2(x-2)(x^2+2x+4)

g (2x-1)(4x^2+2x+1)-4x(2x^2-3)=23

h x(x-2)(x+2)-(x-3)(x^2+3x+9)+1=0

i x(x^2+x+1)-(x-1)(x+1)x=x^2+2

Answer 1

[Nguyễn Huy Tú]

a, \(2\left(x+3\right)\left(x-4\right)=\left(2x-1\right)\left(x+2\right)-27\)

\(\Leftrightarrow2\left(x^2-4x+3x-12\right)=2x^2+4x-x-2-27\)

\(\Leftrightarrow2x^2-2x-24=2x^2+3x-29\Leftrightarrow-5x+5=0\Leftrightarrow x=1\)

b, \(\left(x+2\right)\left(x^2-2x+4\right)-x\left(x-3\right)\left(x+3\right)=26\)

\(\Leftrightarrow x^3-8-x\left(x^2-9\right)=26\Leftrightarrow-8+9x=26\)

\(\Leftrightarrow9x=18\Leftrightarrow x=2\)