GRADIENT OR SLOPE 3

A line passes through (2a, 9) and (8,5a). If its slope is 10, find a.

Solution

x1=2a, y1 = 9, x2 = 8, y2 = 5a

Slope(m) =    y2 – y1

                     x2 – x1

               10 =  5a – 9

                      8 – 2a

               10 =    5a – 9     [cross multiplying]

               1       8 – 2a

10(8 – 2a) = 5a – 9

80 – 20a = 5a – 9

80 – 8a + 9 = 5a

80 + 9 = 5a+ 8a

89 = 13a

89 = 13a

13    13

a= ⁸⁹/13

a= 6 ¹¹/13

Hence a= 6 ¹¹/13

TRY THIS………………….. 

A line passes through (2a, 9) and (3,5a). If its slope is 20, find a.