若2的十次方=a²=4的b次方(a>0时)求(1/4a+1/5b)(1/4a-1/5b)-(1/4a+1/5b)²的值
问题描述:
若2的十次方=a²=4的b次方(a>0时)求(1/4a+1/5b)(1/4a-1/5b)-(1/4a+1/5b)²的值
答
63
答
2^10=a^2=4^b
a=32,b=5
(1/4a+1/5b)(1/4a-1/5b)-(1/4a+1/5b)²
=(8+1)(8-1)-(8+1)^2
=-18