Question

a) 2x - 135 = 245 - 6x

b) 21x + 15 = 215 - 6x

c) \(\frac{x+2}{18}\)= \(\frac{-5}{9}\)

d) \(\frac{x+2}{-20}\)= \(\frac{-5}{x+2}\) 

GIÚP MỊ ZỚI NHA!!!!! >.< 

 

Answer 1

a) \(2x-135=245-6x\)

\(2x+6x=245+135\)

\(8x=380\)

\(x=47,5\)

vậy \(x=47,5\)

b) \(21x+15=215-6x\)

\(21x+6x=215-15\)

\(27x=200\)

\(x=\frac{200}{27}\)

vậy \(x=\frac{200}{27}\)

c) \(\frac{x+2}{18}=\frac{-5}{9}\)

\(\Rightarrow\left(x+2\right).9=18.\left(-5\right)\)

\(\Rightarrow x+2=-10\)

\(\Rightarrow x=-12\)

vậy \(x=-12\)

d) \(\frac{x+2}{-20}=\frac{-5}{x+2}\)

\(\Rightarrow\left(x+2\right)^2=\left(-5\right).\left(-20\right)\)

\(\Rightarrow\left(x+2\right)^2=100\)

\(\Rightarrow\left(x+2\right)^2=10^2\)

\(\Rightarrow x+2=10\)

\(\Rightarrow x=8\)