find the slope and y-intercept of 9x+8y=72?

Question

trying to help son. I need to know how so that I can tell him how to do this. Left his book at school so I have no examples

Answer 1

You just have to get it in the form:y = mx + b, then m will be the slope and b will be the y-intercept.
9x + 8y = 72
Subtract 9x from both sides of the equation:
8y = -9x + 72
Divide both sides by 8:
y = (-9/8)x + 9
So the slope is -9/8 and the y-intercept is 9.

Answer 2

( i know some of this maybe confusing but it might make a little more sense to your son.)

slope intercept form is
y=mx+b


where x and y are a point on a graph.
b is the y-intercept and the slope is whatever number is found in front of the x.

to get it into this form you need to get y by itself.

first subtract the 9x from both sides.
so now we have 8y = -9x+72

now we must divide both sides by 8 to get the 8 away from the y.

put the 8 underneath the whole right side of the equation.


so now we have y= -9/8x + 9

(which will probably make alot more sense to you if you put the negative sign then the 9 on top of the 8 like a typical fraction then the x next to the fraction.)

we divided the -9x by 8. which equals -9/8x and divided the 72 by 8 giving us 9.

now that we have the equation

y= -9/8x + 9

we need to find slope and y intercept (y=mx+b)

m=slope

so slope is -9/8

and b= y intercept

so y intercept= 9




hope this helps. its hard when i cant draw the steps out. but id gladly help you guys with anything else if you are still confused.

Answer 3

The slope of the line is best sought by getting the equation into the "slope intercept form", which is y = ax +b where a is the slope of the line and b is the y intecept.

So
8y = 72-9x
y = 9 - 9/8 x

So when x =0 y=9. and the slope of the line is -9/8.

If you just needed the intercept, you also could have substituted: The intercept is obtained when x=0, so

9(0) + 8y = 72
8y=72
y=9, when x=0.

Hope this helps.

Answer 4

lol looks complicated
1. first you need to get y on one side of the equation by itself so first substract 9x from both sides of the equation
8y= -9x+72

2. your main goal is to get y by itself so now divide everything on the left side of the equation and the right side of the equation by 8
y=-9/8x + 72/8

3. u can still simplify 72 divided 8 so the real answer will be
y= -9/8x + 9

4. to find the slope remember that the number next to x is the slope and the number at the end is the y-intercept so:
slope = -9/8x
y-intercept=9

Answer 5

Slope:
8y=72-9x
y=(72-9x)/8
y=(-9/8x)+9
m=slope= -9/8

y-intercept:
y-intercept means x=0
8y=72-9x
8y=72
y=9

Answer 6

9x+8y=72
-8y -8y subtract 8y form both sides
9x=-8y +72
-72 -72 subtract 72 form both sides
9x-72=-8y
/-8 /-8 divide by negative 8 on both sides
9/8x +9=y

9/8 would be the slope and 9 would be the y intercept!!!

Answer 7

I have been learning this in school recently.

here is an example:

2x-4y=10

first you move the 2x to the other side of the equation

2x-2x-4y=-2x+10

now the equation is -4y=-2x+10

then you divide both sides by -4 ( because the y needs to stand alone)

-4y/4=-2x+10/-4

reduce the fraction -10/4 into -5/2

it is now y=-2x-5/2

The slope is -2 and the y-intercept is -5/2

Hope this helps you understand the concept!