Solve the following system of equations by elimination method
6(ax + by) = 3a + 2b
6(bx - ay) =3b - 2a.
A motor boat whose speed is 24 km/h in still water takes 1 hour more to go 32km upstream than to return downstream to the same spot. Find the speed of the stream.
Let the average speed of train for the first 54 km be x km/h
⇒ Average speed for the next 63 km = ( x + 6) km/h
We know
⇒ 117x + 324 = 3 ( x2 + 6x)
⇒ 117x + 324 = 3x2 + 18x
⇒ 3x2 - 99x -324 = 0 ..(i)
Taking common from the above equation (i)
we have
x2 - 33x - 108 = 0
⇒ x2 - 36x + 3x -108 = 0
⇒ x (x - 36) + 3 (x - 36) = 0
⇒ (x - 36) (x +3 )=0
⇒ x -36 = 0 Or x + 3 =0
x = 36 or x = -3
The speed of the train cannot be negative. Thus, x = 36
Hence, the speed of the train to cover 54 km or its first speed is 36 km/h.
If the points A(k + 1, 2k), B(3k, 2k + 3) and C(5k – 1, 5k) are collinear, then find the value of k.