Question

X+y and x-y if x-y=2 and xy=15

Answer 1

given,x-y=2 and xy=15
⇒x=y+2______(1)
substitute (1) in xy=15
⇒(y+2)y=15⇒y²+2y-15=0
⇒y²+5y-3y-15=0
y(y+5)-3(y+5)=0
(y-3)(y-5)=0
y-3=0;y-5=0
y=3;y=5
now, x=y+2
x=3+2=5;x=5+2=7
∴x+y=5+3=8 or 7+5=12