Question

(2x+3)²-4(x+1)(x-1)=49

Answer 1

Ta có: \(\left(2x+3\right)^2-4\left(x+1\right)\left(x-1\right)=49\)

\(\Leftrightarrow4x^2+12x+9-4\left(x^2-1\right)-49=0\)

\(\Leftrightarrow4x^2+12x-40-4x^2+4=0\)

\(\Leftrightarrow12x-36=0\)

\(\Leftrightarrow12x=36\)

hay x=3

Vậy: x=3

Answer 2

Ta có : \(\left(2x+3\right)^2-4\left(x+1\right)\left(x-1\right)=49\)

=> \(4x^2+12x+9-4x^2+4=49\)

=> \(12x=36\)

=> x = 3

Vậy ...