Question

Решите систему уравнений x - y = 1
x^3 - y^3 = 7

Answer 1

х=1+у 
(1+у)^3-у^3=7
1+3у+3у^2+y^3-y^3=7
3y^2+3y-6=0
D= 9-4*3*(-6)= 9+ 72=81=9^2
y1= (-3+9)/2*3=1
y2=(-3-9)/2*3=-2 
x1=1+1=2
x2=1-2=-1