Question

if x+y+z =9 and x^2+y^2+z^2=35 find the value of x^3 +y^3+z^3-3xyz.

please solve it

step by step
​

Answer 1

Answer:

x+y+z=9

x²+y²+z²=35. (x+y+z)²=x²+y²+z²+2xy+2zx+2yz

or 9²= 35+2(xy+yz+zx)

or 81-35 = 2(xy+yz+zx)

or 46/2 = xy+yz+zx

or -23 = -xy-yz-zx

So,x³+y³+z³-3xyz

=(x+y+z)(x²+y²+z²-xy-yz-zx

=9*(35-23)

=9*12

=108