GRADIENT 4

A line passes through (2a, 10) and (8, 5a). If its slope is 2, find a.

Solution

x1=2a, y1 = 10, x2 = 8, y2 = 5a

Slope(m) =    y2 – y1

                     x2 – x1

               2 =  5a – 10

                      8 – 2a

    2 =    5a – 10     [cross multiplying]

   1       8 – 2a

2(8 – 2a) = 5a – 10

16 – 4a = 5a – 10

16 – 8a + 10 = 5a

16 + 10 = 5a+ 8a

26 = 13a

26 = 13a

13    13

26/13 = a

Hence a = 26/13

TRY THIS.................................

A line passes through (2c, 4) and (1, 4c). If its slope is 6, find c.