Question

(x-1)的平方加(5-x)的平方=15,求(x-1)的平方乘(5-x)的平方.

Answer 1

(x-1)²+(5-x)²=15

[(x-1)+(5-x)]²=(x-1)²+(5-x)²+2(x-1)(5-x)=15+2(x-1)(5-x)=4²=16

所以 2(x-1)(5-x)=16-15=1

得 (x-1)(5-x)=1/2

[(x-1)(5-x)]²=(1/2)²=1/4