Question

A(-1,1) and P(a,b) are two points, where a and b are constants. The gradient of AP is 2. Find an expression for b in terms of a.

Answer 1

b = 2a + 3

Explanation:

Here, we want to write an expression for b in terms of a

Mathematically, the formula for the slope of a line is

m = (y2-y1)/(x2-x1)

m is 2

(x1,y1) = (-1,1)

(x2,y2) = (a,b)

Substituting these values

2 = (b-1)/(a-(-1))

2 = b-1/a + 1

2(a + 1) = b-1

2a + 2 = b- 1

2a + 2 + 1 = b

b = 2a + 3