Question

Find the equation of each of the straight lines, given its gradient and the coordinates of a point on the line.

1. 2, (3,9) 2. 5, (1,8)

Answer 1

1. y=2x+3

2. y=5x+3

Explanation:

1. to find equation of the line we need the gradient and y-intercept

gradient=2

y=mx+c where m is gradient,x and y are coordinates and c is the y-intercept

input given coordinates and gradient in the equation to find c:

9 = 2(3)+c

9 = 6+c

9-6 = c

c = 3

to write the equation we only input gradient and y-intercept:

y=2x+3

2. to find the equation of the line we need the gradient and y-intercept

gradient=5

y=mx+c where m is gradient,x and y are coordinates and c is the y-intercept

input given coordinates and gradient in the equation to find c:

8 = 5(1)+c

8 = 5+c

8-5 = c

c = 3

to write equation we only input gradient and y intercept:

y=5x+3