Question

Tìm x

a)(2x+1)2-4(x+2)2 =9

b)(3x-1)2 +2(x+3)2 +11(x+1)(1-x)=6

c)(x+1)3 - x2 (x+3)=2

d)(x-2)3 -x(x+1)(x-1)+6x2 =5

e)(x-3)(x2 +3x +9)-x(x+4)(x-4)=5

g)(x-2)3 -(x+5)(x2 -5x+25)+6x2 =11

Answer 1

\(\left(2x+1\right)2-4\left(x+2\right)2=9\)

\(4x+2-8x-16=9\)

\(4x-8x=9+16-2\)

\(-4x=23\)

\(x=-\frac{23}{4}\)

Answer 2

a, \(\left(2x+1\right)2-4\left(x+2\right)2=9\)

\(\Leftrightarrow4x+2-8x-16=0\Leftrightarrow-4x-14=0\Leftrightarrow x=-\frac{7}{2}\)

b, \(\left(x+1\right)3-2x\left(x+3\right)=2\)

\(\Leftrightarrow3x+3-2x^2-6x=2\Leftrightarrow-3x+1-2x^2=0\)