Question

if x+y+z=10 and x square - y square- z square=40. find xy+ yz+ zx​

Answer 1

(x+y+z)^2=x^2+y^2+z^2+2xy+2yz+2zx
=>(10)^2=40+2(xy+yz+zx)
=>100-40=2(xy+yz+zx)
=>60/2=xy+yz+zx

xy+yz+zx=30(ans)

I hope it will help u....