writing an equation of a line that passes through two points

[girlpower]

I know the formula for this problem, y=mx+b.

Write the equation of the line which passes through (-1,2) and has a slope of -2. Leave your answer in slope-intercept form.

This is how I showed my work:

-2=1x+b and adding -2+1 and to the other side as well. I don't no know if I started out the problem correctly.

 

[HallsofIvy]

I know the formula for this problem, y=mx+b.

Write the equation of the line which passes through (-1,2) and has a slope of -2. Leave your answer in slope-intercept form.

This is how I showed my work:

-2=1x+b

This is wrong. When you learned that formula, you should have learned that "m" is the slope, Your formula should be y= -2x+ b.
Now set x= -1, y= 2 to determine b.

and adding -2+1 and to the other side as well. I don't no know if I started out the problem correctly.

 

[MarkFL]

Another approach would be to use the point-slope formula since you are given a point and the slope. This formula is:

\(\displaystyle y-y_1=m(x-x_1)\)

The point is \(\displaystyle (x_1,y_1)\) and the slope is \(\displaystyle m\). So, plug in your given data into the formula above, then arrange the resulting linear equation in slope-intercept form.