Question

How do i graph -7x-2y=-21???

Answer 1

-7/2 is the slope. -10.5 is your starting point on the y-axis. You go from -10.5, up 7 and over to the left 2 times because it's negative.

Explanation:

-7x-2y=-21

-2y=7x-21

y=-7/2x-21/2

y=-7/2x-10.5

Hope this helps!

Answer 2

You might want to simplify the equation first. Basically, we'll use y = ax+b instead.

`-7x-2y=-21\\-2y=-21+7x\\y=(-21)/(-2)+(7x)/(-2) \\y=(21)/(2)-(7x)/(2)\\y=(21-7x)/(2)`

Should have been like this then you are able to graph.

To graph, you need to find the x-intercept and y-intercept.

(1) Find x-intercept, substitute y = 0

`0=(21-7x)/(2) \\0=21-7x\\7x=21\\x=3`

Thus, the graph has a x-intercept at (3,0). For those who are wondering where does the fractional 2 go, just multiply the whole equation by 2 to get rid of the fraction.

(2) Find y-intercept, substitute x = 0

`y=(21-7x)/(2)\\ y=(21-0)/(2)\\ y=(21)/(2) \\`

Also 21/2 = 10.5, Thus the graph passes y-axis at (0, 10.5)

Now plot the graph, make a line from x-intercept and y-intercept and you should get like this (Picture below.)