x+y+z =10 then what will xsq+ysq+zsq =40 .find xy+yz+zx
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x + y + z = 10
x^2 + y^2 + z^2 = 40
To find
xy + yz + xz = ?
solution
as we know that
( x + y + z )^2 = x^2 + y^2 + z^2 + 2 ( xy + yz + xz )
10^2 = 40 + 2 ( xy + yz + xz )
100 - 40 = 2 ( xy + yz + xz )
2 ( xy + yz + xz ) = 60
xy + yz + xz = 30
x^2 + y^2 + z^2 = 40
To find
xy + yz + xz = ?
solution
as we know that
( x + y + z )^2 = x^2 + y^2 + z^2 + 2 ( xy + yz + xz )
10^2 = 40 + 2 ( xy + yz + xz )
100 - 40 = 2 ( xy + yz + xz )
2 ( xy + yz + xz ) = 60
xy + yz + xz = 30
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