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当2y-x=5时,5(x-2y)2-3(-x 2y)-100=______.

求七年级上册化简求值,解方程,计算题。。。

化简求值:3ab-4ab 8ab-7ab ab=______. 7x-(5x-5y)-y=______. 23a3bc2-15ab2c 8abc-24a3bc2-8abc=______. -7x2 6x 13x2-4x-5x2=______. .2y (-2y 5)-(3y 2)=______. .(2x2-3xy 4y2) (x2 2xy-3y2)=______. 2a-(3a-2b 2) (3a-4b-1)=______. -6x2-7x2 15x2-2x2=______. 2x-(x 3y)-(-x-y)-(x-y)=______. 2x 2y-[3x-2(x-y)]=______. 5

当2y-x=5时,5(x-2y)^2-3(-x+2y)-100的值是?

5(x - 2y)² -3(-x + 2y) - 100 = 5(2y - x)² -3(2y - x) - 100 = 5×5² - 3×5 - 100 = 125 - 15 - 100 = 10

七年级数学:当2y-x=5时,式子5(x-2y)²-3(-x+2y)-100=

当2y-x=5时,5(x-2y)²-3(-x+2y)-60=________ (过程列出来)

解 2y-x=5 ∴x-2y=-5 ∴5(x-2y)²-3(-x+2y)-60 =5(x-2y)²+3(x-2y)-60 =5×(-5)²+3×(-5)-60 =125-15-60 =50

当2y-x=5时,5(x-2y) 2 -3(-x+2y)-60=______

∵2y-x=5,
∴-x+2y=2y-x=5,x-2y=-(2y-x)=-5,
∴5(x-2y) 2 -3(-x+2y)-60=5×(-5) 2 -3×5-60=125-15-60=50.
故答案是:50.

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