.若n为正整数,且x的2n次方=4,求(5x的2n次方)²-7(x²)的2n次方的值
问题描述:
.若n为正整数,且x的2n次方=4,求(5x的2n次方)²-7(x²)的2n次方的值
答
(5x的2n次方)²-7(x²)的2n次方=5^2*(x^2n)^2-7*(x^2n)^2
=25*4^2-74^2
=25*16-7*16
=16*(25-7)
=16*18
=288