Question

If x2 + y2 + z2 = 24 and xy + yz + zx = 20, find a2 + b2 + c2

Answer 1

Answer:

(x+y+z)²=x²+y²+z²+2xy+2yz+2xz

(x+y+z)²=24+2(xy+yz+xz)

(x+y+z)²=24+2(20)

(x+y+z)²=24+40

(x+y+z)²=64

x+y+z= root 64=8

Answer 2

Answer:

(x+y+Z) ^2= x^2 + y^2 + Z^2+2(Xy+YZ+zX)

(X+Y+Z)^2 = 24+2x20

(X+y+Z)^2 = 24+40

(X+y+z)^2 = 64

(X+Y+z) ^2=8^2

x+y+Z=8