Algebrahard · Past Paper
If x+y+z=6 and x^2+y^2+z^2=14, find xy+yz+zx.
A11
B22
C10
D12
✓ Correct Answer: A — 11
(x+y+z)^2 = x^2+y^2+z^2 + 2(xy+yz+zx). 36 = 14 + 2(Sum). 22/2 = 11.
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