Question

.If x+y = 1 and x-y = 7, find the value of xy​

Answer 1

Step-by-step explanation:

by adding both of the eqn we get 2x=8 or

x=4 and also get y=[1-x]=[-3] . so xy=4×-3=(-12)

Answer 2

Answer:

Given that

X+ Y =1. -------first equation.

X-Y =7. ------- second equation.

From the first equation we concluded that

X=(1-Y)

Now put this value of X in equation 2

(1-Y)-Y=7

1-2Y=7

-2Y=7-1

-2Y= 6

Y= -3

Now,put the value of Y in equation 1 to get the value of X

X=1-(-3)

=4

So, xy= 4 x -3

= -12