Question

Tìm x biết

( 2 3/4 - 1 4/5 ) . x = 1

( x mũ 2 - 9 ) ( 3-5x) = 0

Answer 1

( 2 3/4 - 1 4/5 ) x = 1

=> ( 11/4 - 9/5 ) x = 1

=> 19/20 x = 1

=> x = 1 : 19/20

=> x = 20/19  

Answer 2

x^2 - 9 .( 3 - 5x ) = 0

=> x^-7 . ( 3 - 5x ) = 0

=> x^-7 = 0 hoặc 3 - 5x = 0

=> Mà x^-7 = 0 => x loại

=> 3 - 5x = 0

=> 5x = 3 - 0 = 3

=> x = 3 : 5

=> x = 3/5

Answer 3

\(\left(2\frac{3}{4}-1\frac{4}{5}\right).x=1\)

\(\frac{19}{20}.x=1\)

\(x=1\div\frac{19}{20}\)

\(x=\frac{20}{19}\)

\(\left(x^2-9\right)\left(3-5x\right)=0\)

\(\Rightarrow x^2-9=0\)hoặc\(3-5x=0\)

TH1: \(x^2-9=0\)

\(x^2=0+9\)

\(x^2=9\)

\(x^2=3^2\)

\(\Rightarrow x=3\)

TH2: \(3-5x=0\)

\(5x=3-0\)

\(5x=3\)

\(x=3\div5\)

\(\Rightarrow x=\frac{3}{5}\)

\(\Rightarrow x=3\)hoặc\(x=\frac{3}{5}\)