(1,3) perpendicular to x=0

Question

How to put this in y intercept form?

Answer 1

Normally the y-intercept form is written as:

y = m*x + b

Given we know x = 0, that yields:

y = b

that is, y is any b, which makes sense since x = 0 is literally the y-axis (for any x=0, y can be points along that line, a vertical line which lays atop the y-axis).

A line perpendicular (90') to the y-axis would be a horizontal line. We know that line goes through (1, 3). We also know the slope of a horizontal line is 0. That means logically the line must be y = 3. But let's do it mathematically too:

y = m*x + b
3 = 0*1 + b
3 = b

so again:
y = m*x + b
y = 0*x + 3

must yield

y = 3

for any x.

 

- Greg, from Queens, near Glen Head