5(4у-5)=0 (у-2)(у+1)=0
1) 20y-25=0 20y=25 y=1,25 2) y2+y-2y-2=0 y2-y-2=0 D=(-1)^2-4×1×(-2)=1+8=9 x1=1+3/2×1=4/2=2 x2=1-3/2×1=-2/2=-1