解
x(x-3)-4=0
x²-3x-4=0
(x-4)(x+1)=0
x=4或x=-1
(a²+b²)(a²+b²-3)-4=0
(a²+b²)²-3(a²+b²)-4=0
[(a²+b²)-4][(a²+b²)+1]=0
∵a²+b²≥0
∴a²+b²=4
解
x(x-3)-4=0
x²-3x-4=0
(x-4)(x+1)=0
x=4或x=-1
(a²+b²)(a²+b²-3)-4=0
(a²+b²)²-3(a²+b²)-4=0
[(a²+b²)-4][(a²+b²)+1]=0
∵a²+b²≥0
∴a²+b²=4