Question

What should be added to xy+yz+zx to get -xy -yz-2x?

Answer 1

Step-by-step explanation:

I think you wrote mistake in the question -xy-yz-zx it is not a -xy-yz-2x

let added number be (a)

xy+yz+zx+a=-xy-yz-zx

a=-xy-yz-zx-xy-yz-zx

a=-2xy-2yz-2zx

two is common

a=2(-xy-yz-zx)