Question

Tìm x, biết:
( 12x-5 )( 4x-1 ) + ( 3x-7 )( 1-16x ) = 81

Answer 1

\(\left(12x-5\right)\left(4x-1\right)+\left(3x-7\right)\left(1-16x\right)=81\)

\(\text{⇔}48x^2-32x+5-48x^2-7+115x=81\)

\(\text{⇔}83x-2=81\)

\(\text{⇔}83x=83\)

\(\text{⇔}x=1\)

Vậy: x=1

Answer 2

Ta có: \(\left(12x-5\right)\left(4x-1\right)+\left(3x-7\right)\left(1-16x\right)=81\)

\(\Leftrightarrow48x^2-12x-20x+5+3x-48x^2-7+112x=81\)

\(\Leftrightarrow83x=83\)

hay x=1