5y - 4x = 36?

Question

I don't remember how to do these y=mx+b problems. I got it wrong on my test .

The graph of 5y - 4x = 36 passes through which of the following points? The answer choices are a- (0,-9), b- (4,-4) or d- (-9,0). I took off c- (-4,4) because that's not the right answer.

How do you solve it?

Answer 1

Short cut is just substitute the answers...That's the way I used to solve them in multiple choice questions...That way you get....

First point (0,-9)
5*(-9)-4(0)= -45 so it is not the answer
Second point (4,-4)

5(-4) -4(4) = -20-16 = -36 Not correct
Fourth point: 5(0) - 4(-9) = 36 So this is the correct answer....But looks like the line also passes through your point C (-4,4) !!!
The answer is both (c)(d)

Answer 2

This equation has many solutions which are points(x,y).
Substitute the coordinates of each point into the equation and check if the equation is true. This means both sides of the equation must be equal.
Lets substitute this point (0,9) into the equation.
Left side is 5y -4x = 5(9) -4(0)= 45
Rifgt side is 36 wich does not eqaul the left side. As a result this point is not a solution and the graph does not go through this point.

Same thing for other points. This method is called checking the solution by substituting it on both sides of the equation.

It seems that the right answer is d ( -9,0). Why?

5y -4x =36
5(0) - 4(-9) = 36
0 +36 = 36
36=36

Answer 3

I assume the answer pairs are in the form (x, y).

You can rearrange the equation to be 5y = 4x + 36, then
y = 4/5 x + 36/5 if you want, but I would stick with the first way because it is easier.

Then set x = 0 and solve. 5y = 36, y = 7. Not an answer on the test so discard.

Set y = 0 and solve. 0 = 4x + 36, -4x = 36, x = -9. This is one of the answers (d).

C is also correct! Try it. Check with your teacher, there may be a mistake somewhere.

Answer 4

If you're dealing with a M/C question like this, the easiest way is to remember that graph points are in the (x,y) format... so you can substitute the x and see if the y comes out correct.

D is the correct answer.

Ex. Substitute x = 0 & y = -9, it doesn't work, right? Now try x= -9 and y = 0...

5(0) - 4(-9) = 0 + 36 = 36. 36 = 36. Problem solved.

Answer 5

5y - 4x = 36

turn the equation into the form y=mx+b:

1) 5y - 4x + 4x = 36 +4x
2) 5y = 36 + 4x
3) (5y)/5 = (36)/5 - (4x)/5
4) y = 7.2 - (4/5)x :because 36 / 5 = 7.2

the choices you have, plug it into the equation y=7.2-(4/5)x:

a)(0,9)
9 = 7.2 - (4/5)(0), (0,9) does no work, because 9 does not equal 7.2.

b) (4,4)
4 = 7.2 - (4/5)4
4 = 7.2 - (16/5)
4 = 7.2 - 3.2
4 = 4, this is the answer since when you plug the point into the equation, it solves and 4 = 4.

c) (-4,4)
-4 = 7.2 - (4/5)4
-4 = 7.2 - 3.2
-4 = 4, this won't work, because -4 does not equal 4.

d) (-9,0)
0 = 7.2 - (4/5)(-9)
0 = 7.2 + 7.2, when you multiply 4 x -9 = -36, -36/5 = -7.2
0 = 14.4, because you have 7.2 - (-7.2), which is the same thing as 7.2 + 7.2

your answer is (b) because when you plug in the points you get the correct answer.

good luck.

Answer 6

I think option a and b are correct.
in case a - 5*0-4*-9=36
in case b - 5*4 - 4*-4=36
20+16=36

Answer 7

Ok. First you put it in y=mx+b form. So you put the 4x on the 36 side.

5y=4x+36

Then you divide everything by 5 to get (y) by itself.

y=4x/5 + 36/5

Then you put it in a graphing calculator and use your table. Or you could plug in all of your possible answers and see if they work.

Answer 8

Just plug them in to see if they are solutions
a} 5(-9)-4(0)=36 NO
b} 5(-4)-4(4)=36 YES
d} 5(0)-4(-9)=36 NO

Answer 9

I think its b (4,-4)

replace x in the above expression with 4 and y with -4 gives 36

Answer 10

just substitute the x value of the point into the equation . x equals -9 and y =0