can you please help me solve -4x+y=7

Question

how do you solve this equation

 

Answer 1

Hi Sammy;

Solving for y as Mary did is one resolution.  However, I think there may be another issue.

-4x+y=7

This equation is not in standard form.

Standard form is

 

Ax+By=C A>0, B≠0

 

The > means that A must be greater than zero.  When I was in sixth grade, the way we memorized this symbol is, the alligator is going to eat the bigger one.

 

-4 is not greater than 0.  The alligator in this equation is still hungry.

-4x+y=7

Let's multiply both sides by -1...

-1(-4x+y)=7(-1)

4x-y=-7

 

My guess, and this is only a guess, is that this is what your instructor meant by "solve"---feed the alligator.

 

p.s.  I apologize for the confusion with all my updates.  I had to do some research.  In the standard formula, neither A nor B can equal zero, and A must be greater than zero.  Furthermore, if either A or B is zero, it is no longer a line.  I apologize again.

Answer 2

-4x + y = 7

 

STEP 1: 

Solve for y.

 

Add 4x to both sides.

+4x - 4x + y = 7 + 4x

 

y = 7 + 4x    or    y = 4x + 7

 

You have now solved for y.

 

STEP 2:

Now you are ready to determine (x, y) coordinates.

If x = 0, then y = 7 + 4(0), y = 7

If x = 1, then y = 7 + 4(1), y = 7 + 4, y = 11

and so on ...

 

x   /    y

0   /    7

1   /    11

2   /    ?

3   /    ?

 

Now you can determine slope and rise with the formula

 

y = mx + b

 

where m is the slope and b in the rise.

 

y = 4x + 7

 

slope is 4

rise is 7