y -x =2 and y + x= -2 ,Then ( x+y)(x-y)=?

We want the product of (x+y) and (x-y). We’re given that y+x=-2, so we know we can plug in -2 there.

We need to be careful on the other part. We’re given that y-x=2, and we need to use that to find the value of x-y. Let’s do it by multiplying each side by -1:

y-x=2\\(-1)(y-x)=(2)(-1)\\-y+x=-2\\x-y=-2

There, so now we know that x+y=-2 and x-y=-2. Therefore, (x+y)(x-y)=(-2)(-2)=4.

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