If x-y =5,xy=84,findx+y

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Solution

X-y=5
xy=84
x=5+y
sub x value in xy=84
(5+y)y=84
y2+5y=84
y2+5y-84=0
y=-12 and 7
sub y=-12 in x-y=5
x+12=5
x=5-12=-7
sub y=7 in x-y=5
x-7=5
x=5+7=12
so,
x=-7,12
y=-12,7

so X+Y = -7+-12 = -19
or 7+12 = 19

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