Question

数学题（完全平方公式）

一.填空
1.(a-b)(a-b)=4,ab=0.5,则(a+b)(a+b)=_____
2.(x+y)(x+y)=9，(x-y)(x-y)=5，则xy=_____
3.x·x+2x+y·y-6y=-10，则x=____，y=____
二.简算
1.234×1.234+0.766×0.766+2.468×0.766

Answer 1

一.填空
1.(a-b)(a-b)=4,ab=0.5,则(a+b)(a+b)=__(a-b)²+4ab=6___
2.(x+y)(x+y)=9，(x-y)(x-y)=5，则xy=__[(x+y)²-(x-y)²]/4=1___
3.x·x+2x+y·y-6y=-10
(x+1)²+(y-3)²=0
则x=__-1__，y=__3__

二.简算
1.234×1.234+0.766×0.766+2.468×0.766
=1.234²+2×1.234×0.766+0.766²
=(1.234+0.766)²
=2²
=4