5.4 Equation of a Straight Line (Sample Questions)


Example 1:
Given that the equation of a straight line is 4x + 6y – 3 = 0. What is the gradient of the line?

Solution:
4x + 6y – 3 = 0
6y  = – 4x + 3
y= 4x 6 + 3 6 y= 2 3 x+ 1 2 y=mx+c gradient, m= 2 3 




Example 2:
Given that the equation of a straight line is y = – 7x + 3. Find the y-intercept of the line?

Solution:
y = mx + c, c is y-intercept of the straight line.
Therefore for the straight line y = – 7x + 3,
y-intercept is 3




Example 3:










Find the equation of the straight line MN if its gradient is equal to 3.

Solution:
Given m = 3
Substitute m = 3 and (-2, 5) into y = mx + c.
5 = 3 (-2) + c
5 = -6 + c
c = 11
Therefore the equation of the straight line MN is y = 3x + 11