a-b=2,ab=1则a2+b2=
问题描述:
a-b=2,ab=1则a2+b2=
b gbohn'h
答
由题知,a - b = 2 ,ab = 1
则 (a - b)^2 = 4 (左右均平方)
a^2 - 2ab + b^2 = 4 (展开演算)
a^2 + b^2 = 4 + 2ab
a^2 + b^2 = 4 + 2 * 1 = 6