Question

tìm x

a)(x+7)(3x-1)=x^2-49

 

b)5(x-3)-4=2(x-1)+7

Answer 1

\(a,\left(x+7\right)\left(3x-1\right)=x^2-49\)

\(\left(x+7\right)\left(3x-1\right)-\left(x+7\right)\left(x-7\right)=0\)

\(\left(x+7\right)\left(3x-1-x+7\right)=0\)

\(\left(x+7\right)\left(2x+6\right)=0\)

\(\hept{\begin{cases}x+7=0\\2x+6=0\end{cases}}\)

\(\hept{\begin{cases}x=-7\\x=-3\end{cases}}\)

\(b,5\left(x-3\right)-4=2\left(x-1\right)+7\)

\(5x-15-4=2x-2+7\)

\(5x-19=2x+5\)

\(3x=24\)

\(x=8\)