Question

x+y+z = 8 and xy + yz + zx =20 find
the value of X3 + y3 + z3 - 3xyz please say fast I am writing test ​

Answer 1

Answer:

x + y + z = 8 and xy + yz+ zx = 20.

Squaring, x + y + z = 8 both sides,

we get (x + y + z)2 = (8)2 x2 + y2 + z2 + 2(xy + yz + zx)

= 64 x2 + y2 + z2 + 2 x 20 = 64 x2 + y2 + z2 + 40 = 64 x2 + y2 + z2 = 24 Now, x3 + y3 + z3 – 3xyz = (x + y + z) [x2 + y2 + z2 – (xy + yz + zx)] = 8(24 – 20)

= 8 x 4 = 32 ⇒ x3 + y3 + z3 – 3xyz = 32