Question

Tìm x, biết :

a) x/150 = 5/6 . -7/25

b) 1/2 . x +3/5 . x = 3

c) 25% . x + x = 2 1/2

d) |2x| = 15

Answer 1

a)\(\frac{x}{150}\)=\(\frac{5}{6}\).\(\frac{-7}{25}\)

⇒\(\frac{x}{150}\)=\(\frac{-7}{30}\)

⇒30x=-7.150

⇒x=\(\frac{-1050}{30}\)=-35

vậy x=-35

b)\(\frac{1}{2}\).x+\(\frac{3}{5}.x\)\(=3\)

⇒\(\frac{11}{10}x=3\)

\(\Rightarrow x=\frac{30}{11}\)

Vậy x=\(\frac{30}{11}\)

c)\(25\%.x+x=2\frac{1}{2}\)

\(\Rightarrow\frac{1}{4}.x+x=\frac{5}{2}\)

⇒\(\frac{5}{4}x=\frac{5}{2}\)

⇒\(x=2\)

Vậy\(x=2\)

d)\(\left|2x\right|=15\)

\(\Rightarrow\left[{}\begin{matrix}2x=15\\2x=-15\end{matrix}\right.\)

⇒\(\left[{}\begin{matrix}x=\frac{15}{2}\\x=-\frac{15}{2}\end{matrix}\right.\)

Vậy \(x=\frac{15}{2}\)hoặc \(x=\frac{-15}{2}\)

//học tốt//