Question

Write an equation of the line that passes through (2, −2) and is parallel to the line y=3x+9.

Answer 1

y = 3x - 8

Explanation:

We know that parallel lines have the same gradient. In this situation we want want to work the equation of the line that is parallel to y = 3x + 9 and passes through ( 2 , - 2 ). We know that equations of lines usually go in the format of y = mx + c

↔ Where 'm' is the gradient / slope

↔ Where 'c' is the y - intercept

Using the information in the first sentence we can set up an equation to find the value of 'c'

⇒ Form the equation

→ y = 3x + c

⇒ Substitute ( 2 , -2 ) into the equation to find the value of c

→ -2 = 6 + c

⇒ Minus 6 from both sides to isolate c

→ -8 = c

⇒ Put the value of c back into y = 3x + c

→ y = 3x - 8

So equation of the line that passes through ( 2, −2 ) and is parallel to the line y = 3x + 9 is y = 3x - 8

Answer 2

Explanation:

Parallel lines have the same slope, so we know that our line will have a slope of 3 because y = 3x + 9 has a slope of 3. Now, we can use the point-slope formula of the line to find the equation.

We have y - y₁ = m (x - x₁) (m = 3, x₁ = 2, y₁ = -2)

y- (-2) = 3 (x - 2)

y + 2 = 3x - 6

y = 3x - 8

Hope this helps!