Question

[Hoàng Bảo Sơn]

tìm x 

(75%.x + x )mũ 2 = 1/9

Answer 1

[Hquynh]

\(\left(75\%.x+x\right)^2=\dfrac{1}{9}\\ =>\left(\dfrac{3}{4}x+x\right)^2=\dfrac{1}{9}\\ =>\left[{}\begin{matrix}\left(\dfrac{3}{4}x+x\right)=\dfrac{1}{3}\\\left(\dfrac{3}{4}x+x\right)=-\dfrac{1}{3}\end{matrix}\right.\\ =>\left[{}\begin{matrix}\dfrac{7}{4}x=\dfrac{1}{3}\\\dfrac{7}{4}x=-\dfrac{1}{3}\end{matrix}\right.\\ =>\left[{}\begin{matrix}x=\dfrac{4}{21}\\x=-\dfrac{4}{21}\end{matrix}\right.\)

Answer 2

[Sahara]

\(\left(75\%.x+x\right)^2=\dfrac{1}{9}\)
\(\Rightarrow\left(\dfrac{3}{4}.x+1.x\right)^2=\left(\dfrac{1}{3}\right)^2\)
\(\Rightarrow\dfrac{3}{4}.x+1.x=\dfrac{1}{3}\)
\(\Rightarrow\left(\dfrac{3}{4}+1\right).x=\dfrac{1}{3}\)
\(\Rightarrow\dfrac{7}{4}.x=\dfrac{1}{3}\)
\(\Rightarrow x=\dfrac{1}{3}:\dfrac{7}{4}\)
\(\Rightarrow x=\dfrac{4}{21}\)