Question

tìm x,y,z

\(\frac{x}{3}=\frac{y}{4}=\frac{z}{5}và2x^2+2y^2-3z^2=100\)

Answer 1

ta co : 

x/3=y/4=z/5 => 2x^2/36=2y^2/64=3z^2/225 va 2x^2+2y^2-3z^2=100

Ap dung tinh chat day ti so bang nhau  :

2x^2/36=2y^2/64=3z^2/225 = 2x^2+2y^2-3z^2/36+64-225=100/-125=-0,8

Suy ra : 

2x^2/36=-0,8 => 2x^2= -0,8 . 36:2=-14,4 => x= tu tih nhe so ma co the bang mu 2 y 

2y^2/64=-0,8=> 2y^2 = -0,8.64:2=- 25,6  => x= nhu tren nhe

3z^2/225=-0,8=>3z^2=-0,8.225:3=-60 = > x = nhu tren nhe 

lik e