Question

The midpoint of the line segment joining A(2a, 4) and B(–2, 3b) is C(1, 2a + 1). Find the values of a and b.

Answer 1

The points are A (2a, 4) and B (-2, 3b).

Let  C ( 1,2a + 1) be the mid-point of AB. Then:

` x = (x_1 +x_2) /2 , y = (y_1 +y_2)/2`

` ⇒ 1= (2a (-2))/2 , 2a +1 =(4+3b)/2`

`⇒ 2=2a-2, 4a +2 =4+3b`

⇒2a -2+2, 4a -3b = 4-2

`⇒ a = 4/2 , 4a -3b =2 `

⇒ a =2, 4a -3b =2

Putting the value of a in the equation 4a +3b =2 , we get:

4(2) - 3b =2

⇒ -3b = 2-8=-6

`⇒ b = 6/3 = 2`

Therefore,  a =2  and  b= 2