Question

if x = 1, y = 3 and z = 1, then find the value of xy + yz - 2​

Answer 1

Answer:

4

Step-by-step explanation:

xy + yz - 2

=1×3+3×1-2

=3+3-2

=6-2

=4

Please mark my answer as brainliest

Answer 2

Answer:

like my answer follow me mark as brainlist

Step-by-step explanation:

Identity:x3 +y3 +z3 -3xyz = (x+y+z)( x2 +y2 +z2 -xy-yz-zx)

Since x + y + z = 1, xy + yz + zx = -1and xyz= -1,

Putting values, we get:

So

Now

(x+y+z)2 = x2 +y2 +z2 +2xy +2yz +2zx

12 = x2 +y2 +z2 +2(-1)

x2 +y2 +z2 = 3

Put in eq (i)

x3 +y3 +z3 =3-2 = 1