Question

Tìm x:

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

Answer 1

\(\left(x+4\right)^2-\left(x+1\right)\left(x-1\right)=16\)

\(\Rightarrow x^2+8x+16-x^2+1=16\)

\(\Rightarrow\left(x^2-x^2\right)+8x+16-16+1=0\)

\(\Rightarrow8x+1=0\)

\(\Rightarrow8x=-1\)

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

Answer 2

(x+4)²-(x+1)(x-1)=16

\(\Leftrightarrow\)x²+8x+16-x²+1=16

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

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

\(\Leftrightarrow\)8x=-1

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