若a+b=17,ab=60,求a2+b2和(a-b)2的值.
问题描述:
若a+b=17,ab=60,求a2+b2和(a-b)2的值.
答
a2+b2=(a+b)2-2ab
=172-2×60
=289-120
=169;
(a-b)2=(a+b)2-4ab
=172-4×60
=289-240
=49.