Question

Tìm x:

(2x+1)^2-4(x+2)^2=9

Answer 1

\(=>\left(2x\right)^2+2.2.1x+1^2-4\left(x^2+2.2.x+2^2\right)=9\) 9

\(=>4x^2+4x+1-4x^2-16x-16=9\)

\(=>-12x-15=9\)

\(=>-12x=24\)

\(=>x=-2\)

Answer 2

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

\(\Rightarrow4x^2+4x+1-4\left(x^2+4x+4\right)=9\)

\(\Rightarrow4x^2+4x+1-4x^2-8x-16=9\)

\(\Rightarrow-4x-15=9\)

\(\Rightarrow-4x=24\)

\(\Rightarrow x=-6\)

Answer 3

(2x+1)^2−4(x+2)^2=9

⇒4x^2+4x+1−4(x^2+4x+4)=9

⇒4x^2+4x+1−4x^2−8x−16=9

⇒−4x−15=9

⇒−4x=24

=> x=-6