Question

The midpoint of (4,y) and (x,-8) is 7.-9), then x+y =​

Answer 1

Since, (−2,−4) is the midpoint of (6,−7) and (x,y).

⇒ 2x+6=−2⇒x=−10and2y−7 =−4⇒y=−1

Answer 2

x= 10  

y=-10

X+Y =0

Step-by-step explanation:

To find x and y,

FORMULA OF MIDPOINT:  

$(\frac{x_{1}+ x_{2} }{2},\frac{y_{1} +y_{2} }{2} )=(x,y)$

Given values:

$(x_{1}, y_{1} )=(4,y)$

$(x_{2}, y_{2} )=(x,-8)$

Apply the given values in the mid point formula

==>   $(\frac{x_{1}+ x_{2} }{2},\frac{y_{1} +y_{2} }{2} )=(x,y)$

==>   $(\frac{4+ x }{2},\frac{y -(-8) }{2} )=(7,-9)$

we have to find the x and y values,

==>  $(\frac{4+ x }{2},\frac{y +8) }{2} )=(7,-9)$

Equating x values

==>  $(\frac{4+ x }{2} )=7$

==>   $\frac{4+ x }{2} =7$

==>   4+x = 7×2

==>    4+x = 14

==>   x= 14-4

==>  x=10

Equating y values

==>   $\frac{y +8 }{2} =-9$

==>   y+8 = -9×2

==>   y+8 = -18

==>   y =-18-8

==>  y=-10

X+Y = 10-10

X+Y =0