Question

if x+y+z=11 and x^2+y^2+z^2=81, find the value of xy+yz+zx



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Answer 1

Answer:

20

Step-by-step explanation:

(x+y+z)^2 = x^2+y^2+z^2+2(xy+yz+zx)

11^2 = 81 + 2(xy+yz+zx)

121 = 81 + 2(xy+yz+zx)

2(xy+yz+zx) = 40

xy+yz+zx = 20

Answer 2

Answer:

Answer = 20

Step-by-step explanation:

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