Question

已知x=y+3，求代数式的值。

4分之一（x-y）的平方-0.3（x-y）+0.75（x-y）的平方+10分之3（x-y）-2（x-y）+7的值

Answer 1

x=y+3,则x-y=3
4分之一（脊知x-y）的平方-0.3（x-y）+0.75（x-y）游兄的平方樱磨消+10分之3（x-y）-2（x-y）+7
=0.25(x-y)²+0.75(x-y)²-0.3(x-y)+0.3(x-y)-2(x-y)+7
=(x-y)²-2(x-y)+7
=3²-2×3+7
=9-6+7
=10

Answer 2

x=y+3
则x-y=3
4分余猛锋之一（x-y）的平方知谨-0.3（x-y）+0.75（x-y）的竖晌平方+10分之3（x-y）-2（x-y）+7
=1/4*(x-y)^2-0.3(x-y)+0.75(x-y)^2+3/10*(x-y)-2(x-y)+7
=1/4*(x-y)^2-3/10*(x-y)+3/4*(x-y)^2+3/10*(x-y)-2(x-y)+7
=(1/4+3/4)*(x-y)^2-2(x-y)+7
=(x-y)^2-2(x-y)+7
=(x-y)(x-y-2)+7
=3*(3-2)+7
=3+7
=10

Answer 3

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