Question

Answer 1

a)25x²-12=2²x 5+(-2)²

25x²-12=24

25x²=36

25x²-36=0

(5x)²-6²=0

(5x-6)(5x+6)=0

\(\Rightarrow\left[{}\begin{matrix}5x-6=0\\5x+6=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}5x=6\\5x=-6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{6}{5}\\x=-\dfrac{6}{5}\end{matrix}\right.\)

Vậy tập nghiệm của phuông trình là S=\(\left\{\dfrac{6}{5};-\dfrac{6}{5}\right\}\)

Answer 2

(x+4)²-(1+x)(x-1)=16

\(\Rightarrow\)x²+8x+16-(x²-1)=16

\(\Rightarrow\)x²+8x+16-x²+1=16

\(\Rightarrow\)8x+17=16

\(\Rightarrow\)8x=16-17

\(\Rightarrow\)8x=-1

\(\Rightarrow\)x=\(\dfrac{-1}{8}\)