1.49-(-20.6)-3/5 2.31+(-5/4)+0.25 3.(-6/5)-7-(-3.2)+(-1)

super20072022-10-04 11:39:541条回答

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echobrigita 共回答了16个问题 | 采纳率93.8%
1.49-(-20.6)-3/5
=49+(20.6-3/5)
=49+20
=69
2.31+(-5/4)+0.25
=31+(-5/4+0.25)
=31-1
=30
3.(-6/5)-7-(-3.2)+(-1)
=(-6/5+3.2)-(7+1)
=2-8
=-6
1年前

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先分解因式,再求值
1.25x(0.4-y)^2-10y(y-0.4)^2,其中x=0.04.y=2.4
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(a-b)(3a+b)^2+(a+3b)^2(b-a)
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=(a-b)[(3a+b)^2-(a+3b)^2]
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=8(a-b)^2(a+b)
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=[3a-3b+2a+2b]^2
=(5a-b)^2
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=25x(0.4-y)^2-10y(0.4-y)^2
=(25x-10y)(0.4-y)^2
=5(5x-2y)(0.4-y)^2
=5(0.2-4.8)(0.4-2.4)^2
=5*(-4.6)*4
=20*(-4.6)
=-92
(a^2+b^2)^2-4a^2b^2,其中a=3.5,b=1.5
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