Graphs 1

4 marks · Hard

The straight line L passes through the points (–5, 7) and (3, –9).

(a)

Calculate the gradient of line L.

[2 marks]

(b)

Find the equation of line L in the form .

[2 marks]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

(a) -2

(b) y = -2x - 3

Common mistakes: Sign errors in gradient; Using wrong coordinates to find y-intercept

Show mark scheme and worked solution

Marking points

M1 (a) · 1 mark · Correct substitution into gradient formula ().

A1 (a) · 1 mark · Correct calculation of gradient as -2.

M2 (b) · 1 mark · Uses correct gradient with one point to substitute into or equivalent method. (follow-through)

A2 (b) · 1 mark · Gives final equation as . (follow-through)

Worked solution

a) Gradient =

b) Use point (3, –9):

Equation: