1.5a+3[2b-3(a-b+2c)-(b+c)] 2.4x²-[2x-(x²-2x+3)-2(x

aaa555yyy2022-10-04 11:39:541条回答

1.5a+3[2b-3(a-b+2c)-(b+c)] 2.4x²-[2x-(x²-2x+3)-2(x²-3x)]

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uuttiqq 共回答了16个问题 | 采纳率81.3%
5a+3[2b-3(a-b+2c)-(b+c)]
=5a+3(2b-3a+3b-6c-b-c)
=5a+6b-9a+9b-18c-3b-3c
=(5a-9a)+(6b+9b-3b)-(18c+3c)
=-4a+12b-21c

4x²-[2x-(x²-2x+3)-2(x²-3x)]
=4x²-(2x-x²+2x-3-2x²+6x)
=4x²-2x+x²-2x+3+2x²-6x
=(4x²+x²+2x²)-(2x+2x+6x)+3
=7x²-10x+3
1年前

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1.5a+(2-4a)=0 1.5a+2-4a=0 1.5a-4a=-2 -2.5a=-2 a=2除以2.5
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遇到这种,你就只认这个公式:(a+b)^2=a^2+b^2+2*a*b.
(4x-3y)^2中a=4x,b=-3y,代进去后就得到结果了.
(1)(4x-3y)^2 (2)(1.5a-2/3b)^2 (3)(25x^3+15^2-20x)÷(-5x) (4)(
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(1)(4x-3y)^2 =(4x)²-2×4x×3y+(3y)²=16x²-24xy+9y²

(2)(1.5a-2/3b)^2=2.25a²-2ab+4b²/9

(3)(25x^3+15x^2-20x)÷(-5x)
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(5)(8a^3b-5a^2b^2)÷4ab
=8a^3b÷4ab -5a^2b^2 ÷4ab
=2a²-5ab/4

(6)(2a)^3×b^4÷12a^3b^2
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(7)(6/5a^3x^4-0.9ax^3)÷3/5ax^3
=6/5a^3x^4÷3/5ax^3-0.9ax^3 ÷3/5ax^3
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b=(1.5a+400)/4
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∵Ia-2I +(b+3)²=0,
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=3a²b - (2ab²-2ab+3a²b+ab)+3ab²
=3a²b - 2ab²+2ab-3a²b-ab+3ab²
=ab²+ab
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=12