已知x+y=30,x-y=20,求2(x-2y)的二次方-132的值?
问题描述:
已知x+y=30,x-y=20,求2(x-2y)的二次方-132的值?
答
x+y=30,x-y=20
解得x=25,y=5
∴2(x-2y)³-132
=2*(25-2*5)²-132
=450-132
=318