Question

tìm x

a, \(\dfrac{x+1}{2}=\dfrac{8}{x+1}\)

Answer 1

\(\dfrac{x+1}{2}+\dfrac{8}{x+1}\\ \left(x+1\right)^2=2\cdot8=16=4^2=\left(-4\right)^2\\ x+1=\left[{}\begin{matrix}4\\-4\end{matrix}\right.\Rightarrow x=\left[{}\begin{matrix}3\\-5\end{matrix}\right.\)

Vậy có hai giá trị của x là ...

Answer 2

\(\dfrac{x+1}{2}\)=\(\dfrac{8}{x+1}\)

(x+1)(x+1)=2.8

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

(x+1)\(^2\)=(\(\pm\)4)\(^2\)

=> x+1=4 hoặc x+1=-4

*x+1=4 *x+1=-4

x=3 x=-5

Vậy x=3 hoặc x=-5