先化简,再求值:[(x-y)2+(x+y)(x-y)]÷2x,其中x=3,y=-1.5.
题型:解答题难度:一般来源:江西
先化简,再求值:[(x-y)2+(x+y)(x-y)]÷2x,其中x=3,y=-1.5. |
答案
解法一:[(x-y)2+(x+y)(x-y)]÷2x, =[(x-y)(x-y)+(x+y)]÷2x, =(2x2-2xy)÷2x, =x-y, 当x=3,y=-1.5时,原式=3-(-1.5)=4.5;
解法二:[(x-y)2+(x+y)(x-y)]÷2x, =[(x2-2xy+y2)+(x2-y2)]÷2x, =(2x2-2xy)÷2x, =x-y, 当x=3,y=-1.5时,原式=3-(-1.5)=4.5. |
举一反三
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