Question

Tìm x biết :

\(X^2\)+10x+8=0

Answer 1

\(x^2+10x+8=0\)

\(\Delta=10^2-4\left(1\cdot8\right)=68\)

\(\Rightarrow x_{1,2}=\frac{-10\pm\sqrt{68}}{2}\)

Chưa học thì phân tích sau:

\(x^2+10x+8=0\Leftrightarrow x^2+10x+25-17=0\)

\(\Leftrightarrow\left(x+5\right)^2-17=0\)

\(\Leftrightarrow x=\pm\sqrt{17}-5\)

 

Answer 2

\(x^2+10x+25=17\\ \leftrightarrow\left(x+5\right)^2=17\\ \leftrightarrow x=\sqrt{17}-5\)

Hay \(x=-\sqrt{17}-5\)

Answer 3

x^2+10x+8=0

=>(x^2+10X+25)-25+8=0

=>(x-5)^2=17

=>x-5=\(\sqrt{17}\)

=>x=\(\sqrt{17}+5\)

Answer 4

cảm ơn các bạn nhìu nha