16
a)
5(x+1)+7=3(y-5)+y+3
(x+y)(x-y)=(x+1)^2-(y-2)^2
5x+5+7=3y-15+y+3
x^2-y^2=x^2+2x+1-y^2+4y-4
5x+12=4y-12
x^2-x^2-y^2+y^2=2x+4y-3
5x-4y=-24
2x+4y=3
(le adunam) =>
=>7x=-21 => x=-3
2×(-3)+4y=3
-6+4y=3
4y=9
y=9/4.
17.
x+yrad2=2rad2
3/rad2×x-2y=1
x=2rad2-yrad2
x=rad2(2-y)
3/rad2× rad2(2-y)-2y=1
3×(2-y)-2y=1
6-5y=1
y=1;
x=rad2(2-1)
x=rad2
rad=radical
