Question

What is the equation of the line which passes through the point (-1,2) and is parralel to the line y = x + 4

Answer 1

Explanation:

y = mx+ c

y = x + 4

m = 1

Parallel means m1 = m2

and we know that (-1, 2) = (x, y)

y - y1 = m (x - x1)

y - 2 = 1 (x + 1)

y - 2 = x + 1

y = x + 1 + 2

y = x + 3

#CMIIW

Answer 2

`\large\textrm{y = x + 3}`

Further explanation

We know the slope of the line, it's 1.

How did I figure this out?

The given equation is in slope-intercept form: y = mx + b, in which x and y are the co-ordinates of the point which the line passes through and m and b are the slope and y-intercept, respectively.

Also the slopes of parallel lines are always the same.

So 1 is the slope.

Basically, we know m but we don't know b, so let's go ahead and find it.

Plug in 2 for y:

`2=x+b`

Plug in -1 for x:

`2=-1+b`

We have a little equation that we can solve in terms of b:

`-1+b=2`

`b=2+1`

`b=3`

The y-intercept is 3; that makes the line's equation y = x + 3.