Help please. I don’t understand

A simple way of doing this is to first make an equation in point-slope form, and then convert that equation to slope-intercept form. As the name says, you only need a point and a slope.

The point-slope form is y - y1 = m(x - x1)
Plug in the values to give you: y - 8 = -3(x - 7)
Now use the distributive property to give you: y - 8 = -3x + 21
Finally, add 8 to both sides to isolate the y, and you're finished: y = -3x + 29

Hope this helps! :)

marksorace marksorace · Answer 2 · 2017-10-12T04:24:54+02:00

Hi,

To find the equation you have to realize the slope formula is y=mx+b.
M being the slope, and b being the y-intercept.

If the slope must be -3, you must plug -3 into m. In this case, there is only one option with -3 as the slope so the answer is y=-3x+29.

But, to find the equation of a function that passes through a certain point, you plug in your x and y values into your function y=mx+b.

In this question it would be 8=-3(7)+b which becomes 8=-21+b then 29=b.

Finally, plug in just the slope and y-intercept to find the equation: y=-3x+29