Question

State the equation of the line which has the y-intercept :

a) 2 and slope 7 .
b) -1 and is parallel to y= 5x - 7.
c) 2 and is inclined at 45 degree to the x- axis. ​

Answer 1

A general line is written as:

y = a*x + b

where:

a is the slope

b is the y-intercept.

a) y-intercept = 2 and slope = 7.

This line is:

y = 7*x + 2

b) y-intercept = -1 and is parallel to y= 5x - 7.

Now, if two linear equations are parallel if they have the same slope and different y-intercept. Then if we want a line parallel to y= 5x - 7, this means that the slope of this line must also be equal to 5.

y = 5*x + (-1)

c) y-intercept 2 and is inclined at 45° to the x- axis. ​

When we have an inclination of A degrees from the x-axis, the slope of the equation is given by: a = Tan(A)

In this case, we have A = 45°

Then the slope is a = Tan(45°) = 1

Then the equation of this line is:

y = 1*x + 2