Question

(a-4)3次方-16-12(a-4)=0 a=?

Answer 1

设a-4=x

∴x³-12x-16=0

x³+2x²-2x²-4x-8x-16=0

x²(x+2)-2x(x+2_-8(x+2)=0

(x+2)(x²-2x-8)=0

(x+2)²(x-4)=0

∴x=-2 x=4

∴a-4=-2 a-4=4

a=2或a=8