(-1,-9) and (2,21) into an equation

y=10x+1

Step-by-step explanation:

subtract to get a slope of 10

insert the slope into the equation with one of the points. 21=10(2)+b

then solve 21=20+b   b=1

place slope and y-intercept ito the equation. y=10x+1

When dividing by 10, 100, 1000 and so on, move the decimal point to the left as many places as there are 0s. So when dividing by 10, move the decimal point one place, by 100 two places, by 1000 three places and so on.