Question

How do you write an equation in standard form given point (1,-1) and (3,5)?

Answer 1

Standard form is `ax+by=c` but you are only given 2 points so you cannot write 3 equations to solve for, a, b, and c. You must use the points to find the slope and then convert the point-slope form.

Explanation:

Use the two points to find the slope:

`m = (y_1-y_0)/(x_1-x_0)`

`m = (5 - -1)/(3-1)`

`m = 6/2`

`m = 3`

Use the point-slope form for the equation of a line:

`y=m(x-x_1)+y_1`

`y=3(x-3) + 5`

Now convert to standard form:

`y = 3x-9+5`

`y = 3x-4`

`3x-y=4" "larr` standard form