SLOPE OR GRADIENT 1

A line passes through (2a, 3) and (8,-3a). If its slope is 4, find a.

Solution

x1=2a, y1 = 3, x2 = 8, y2 = -3a

Slope(m) =    y2 – y1

                     x2 – x1

               4 =  -3a – 3

                      8 – 2a

               4 =    -3a – 3     [cross multiplying]

               1       8 – 2a

4(8 – 2a) = -3a – 3

32 – 8a = -3a – 3

32 – 8a + 3 = -3a

32 + 3 = -3a+ 8a

35 = 5a

35 = 5a        [Dividing by 5 both sides]

5      5

7 = a

Hence a = 7

TRY THIS………………………………

A line passes through (2n, 9) and (8,-3n). If its slope is 5, find n.