The points (-3,9) and (-1,r) lie on line with slop -2.

The value of r is 5

Step-by-step explanation:

The question is

Find out the value of r

we know that

The formula to calculate the slope between two points is equal to

we have the points

(-3,9) and (-1,r)

substitute

Remember that

substitute the value of m

Solve for r

Multiply by 2 both sides

Adds 9 both sides

Rewrite

assuming you mean addition: addition and subtraction are reverse operations.

step-by-step explanation:

because linear equations are a lot simpler than quadratics equations, and linear equations formula is a lot easier to memorize. that's why i think they're harder.