如果ab=2,a+b=3,求:(1)(a-b)²;的值.(2)a²+b²的值
100²-99²+98²-97²+......+2²-1²
=
【x+y-4】+(xy-3)²=0,求x²+y²
=
人气:119 ℃ 时间:2019-09-23 20:39:48
解答
1.
(a-b)²
=(a+b)²-4ab
=3²-4×2
=9-8
=1
2.
a²+b²
=(a-b)²+2ab
=1+2×2
=1+4
=5100²-99²+98²-97²+......+2²-1²=【x+y-4】+(xy-3)²=0,求x²+y²=100²-99²+98²-97²+......+2²-1²=(100-99)(100+99)+(98-97)(98+97)+...+(2-1)(2+1)=100+99+98+97+...+2+1=(100+1)*100/2=5050【x+y-4】+(xy-3)²=0你那个黑乎乎的括号,应该是绝对值吧?|x+y-4|+(xy-3)²=0绝对值与平方数都是非负数两个非负数的和等于0,这两个数都等于0x+y-4=0xy-3=0x+y=4xy=3x²+y²=(x+y)²-2xy=4²-2×3=16-6=10
推荐
- 已知a²b²+a²+b²+1=4ab,求ab的值
- 已知a(a-1)-(a²-b)=2,求(a²+b²)/2-ab的值
- 已知ab=9,a-b=-3,则a2+3ab+b2的值为_.
- 已知a+b=9,a-b=3,求a²+b²和ab的值
- 已知ab/a+b=1/3,求1/a²+1/b²的值
- That was ___that i had no choice but to call the police
- 甲,乙两位同学共有28本书,如果甲拿3本给乙,那么两人的书就一样多,若设甲原有书x本,则乙原有书多少
- why did you leave him behind?You ___ him with you.
猜你喜欢