+845 The points A, B and C lie on the straight line y= 2x-1
The coordinates of a are (2, 3)
The coordinates of B are (5, 9)
Given that AC = 3AB, find the coordinates of C
+128473 C = [ 2 + ( 5 -2)*3 , 3 + (9 - 3)*3 ] = [ 2 + 9, 3 + 18 ] = ( 11, 21 )
+128473 OK
We need to find the difference between the x coordinates of A and B= (5 -2) =3
Since AC = 3AB
3 times this difference plus the x coordinate of A will give us the x coordinate of C
So 3(5-2) + 2 = 3*3 + 2 = 11
Similarly.......3 times the difference between the y coordinates of A and B plus the y coordinate of A will give us the y coordinate of C....so we have
3 ( 9 - 3) + 3 = 3*6 + 3 = 21
So....the coordinates of C are (11, 21)
