Question

[Nguyễn Mai Nhan Ngọc]

cho 3 số dương x y z biết \(\frac{x}{3}=\frac{y}{5}=\frac{z+1}{2}\) biết \(2x^2+y^2+2z^2+4z=202\) .Tính x+y-z

Answer 1

[Devil]

\(\frac{x}{3}=\frac{y}{5}=\frac{z+1}{2}=k\Rightarrow x=3k;y=5k;z=2k-1\)

ta có:\(2.\left(3k\right)^2+\left(5k\right)^2+2\left(2k-1\right)^2+4\left(2k-1\right)=202\)

\(18k^2+25k^2+8k^2-2+8k-4=202\)

\(59k^2-6=202\)

\(59k^2=208\)

...