1、计算(化简):(1)-(4a²-3ab+b²)+(-3a²+4ab-2b²)
来源:学生作业帮 编辑:搜搜考试网作业帮 分类:数学作业 时间:2024/08/19 01:24:53
1、计算(化简):
(1)-(4a²-3ab+b²)+(-3a²+4ab-2b²)
(2)a-(2a-b)-2(a+2b)
2、先化简,再求值:
(1)当x=-5时,求5x+3x²-(2x-2x²-1)的值.
(2)4(a²-3a)-(2a²+a-1)+(2-a²+4a),其中a=-2.
(注意:1、2、题都要写过程,)
(1)-(4a²-3ab+b²)+(-3a²+4ab-2b²)
(2)a-(2a-b)-2(a+2b)
2、先化简,再求值:
(1)当x=-5时,求5x+3x²-(2x-2x²-1)的值.
(2)4(a²-3a)-(2a²+a-1)+(2-a²+4a),其中a=-2.
(注意:1、2、题都要写过程,)
![1、计算(化简):(1)-(4a²-3ab+b²)+(-3a²+4ab-2b²)](/uploads/image/z/15752725-61-5.jpg?t=1%E3%80%81%E8%AE%A1%E7%AE%97%EF%BC%88%E5%8C%96%E7%AE%80%EF%BC%89%EF%BC%9A%EF%BC%881%EF%BC%89-%284a%26%23178%3B-3ab%2Bb%26%23178%3B%29%2B%28-3a%26%23178%3B%2B4ab-2b%26%23178%3B%29)
解
1、计算(化简):
(1)-(4a²-3ab+b²)+(-3a²+4ab-2b²)
=-4a²+3ab-b²-3a²+4ab-2b²
=(-4a²-3a²)+(3ab+4ab)+(-b²-2b²)
=-7a²+7ab-3b²
(2)a-(2a-b)-2(a+2b)
=a-2a+b-2a-4b
=(a-2a-2a)+(b-4b)
=-3a-3b
2、先化简,再求值:
(1)当x=-5时,求5x+3x²-(2x-2x²-1)的值.
=5x+3x²-2x+2x²+1
=(5x-2x)+(3x²+2x²)+1
=5x²-3x+1
=5×(-5)²+3×(-5)+1
=125-15+1
=111
(2)4(a²-3a)-(2a²+a-1)+(2-a²+4a),其中a=-2.
=4a²-12a-2a²-a+1+2-a²+4a
=(4a²-2a²-a²)+(-12a-a+4a)+3
=a²-9a+3
=(-2)²-9×(-2)+3
=4+18+3
=25
1、计算(化简):
(1)-(4a²-3ab+b²)+(-3a²+4ab-2b²)
=-4a²+3ab-b²-3a²+4ab-2b²
=(-4a²-3a²)+(3ab+4ab)+(-b²-2b²)
=-7a²+7ab-3b²
(2)a-(2a-b)-2(a+2b)
=a-2a+b-2a-4b
=(a-2a-2a)+(b-4b)
=-3a-3b
2、先化简,再求值:
(1)当x=-5时,求5x+3x²-(2x-2x²-1)的值.
=5x+3x²-2x+2x²+1
=(5x-2x)+(3x²+2x²)+1
=5x²-3x+1
=5×(-5)²+3×(-5)+1
=125-15+1
=111
(2)4(a²-3a)-(2a²+a-1)+(2-a²+4a),其中a=-2.
=4a²-12a-2a²-a+1+2-a²+4a
=(4a²-2a²-a²)+(-12a-a+4a)+3
=a²-9a+3
=(-2)²-9×(-2)+3
=4+18+3
=25
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