Question

if p(-1,1) is the midpoint of the line segment joining (-3,6) and B (1,b+4) , then what is the the value of b.

Answer 1

Solution :

Let A( -3 , 6 ) = ( x1 , y1 ) ,

B( 1 , b + 4 ) = ( x2 , y2 ) ,

P( -1 , 1 ) = ( x , y )

It is given that ,

P is the midpoint of Line segment

joining points A and B .

We know that ,

( y1 + y2 )/2 = y


=> ( 6 + b + 4 )/2 = 1

=> ( 10 + b ) = 2

=> b = 2 - 10

=> b = -8

••••

Answer 2

Mid point of the line segment joining A(-3,6) and B(1,b+4),

Mid pt. of AB = (-3+1/2 , b+4+6/2)

=(-2/2, 10+b/2)

=(-1 , 10+b/2)

(-1,1) = (-1, 10+b/2)

this implies, (10+b)/2. =1


10+b = 2

b= -8.
Hope it helps......