[Math-70 Elementary/Highschool Algebra: Graphically solving a system of linear equations] Do I make the 4 into a -4 ?

[u/Fine_Two_923]

Hey so this might seem like a silly question but I want to know if you have a -x = 4 if it turns into a -4. I have the other parts of the graphing completed it’s just this part that I don’t want to make a mistake on!!! Thank you in advance

P.S- the reason it’s says elementary/highschool math is because I am taking a beginner math class not a algebra class In elementary

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[u/Temporary_Pie2733]

Where are you getting -x in the first place? x - 0 = 4 simplifies directly to x = 4.

[u/Plane_Tailor7168 → u/Temporary_Pie2733]

yes thats what i was comfused about lol

[u/Wooden-Hornet2115 → u/Plane_Tailor7168]

What I'm confused about is OP saying they have a system of linear equations, when they only have one equation.

[u/Plane_Tailor7168]

it should just be x=4

[u/Broad-Raspberry-6296 → u/Plane_Tailor7168]

You’re right. He made a mistake from 2nd to 3rd line. x-0=4 is x=4 lol

[u/Plane_Tailor7168 → u/Plane_Tailor7168]

in the equation, if it was -x=4 then x=-4

[u/Independent_Prior612 → u/Plane_Tailor7168]

Yes but the x doesn’t become negative.

[u/Delanq]

Theoretically if you had -x=4, you could multiple both sides by -1 to get x = -4. HOWEVER. You don’t have that from this equation. You have: x - 4*0=4. That simplified to x-0=4 or simply x=4

[u/Wooden-Hornet2115]

Are you trying to fimd the X-intercept? You don't have a system of equations, you have an equation.

Also, yes if -x = 4, x = -4. In this specific equation, x = 4. I don't know how you got -x = 4.

[u/slayyerr3058]

In -x = 4, there is an invisible negative one as the coefficient on the x. Divide both sides by negative one to remove it.

[u/Plane_Tailor7168 → u/slayyerr3058]

i think you missunderstood him (or im just an idiot)

[u/Plane_Tailor7168 → u/Plane_Tailor7168]

wait no im sorry but i think he messed up in the image bc it should just be x=4

[u/Dtrain8899]

Why do you have -x? Should just be x

[u/eileyle]

If you have -x = 4, then it's shorthand for -1 times x = 4, therefore you divide both sides by -1 to get x = -4.

However, you screwed up.

x - 4 times 0 = 4

4 times 0 should be 0

leading to

x - 0 = 4

which is the same as

x = 4

You should not have gotten -x = 4.

[u/Serafim91]

"-x" is actually "+(-1)*x". The -1 is the same as any other coefficient and can be multiplied and divided as needed following the same rules.

[u/wijwijwij]

If you are seeking an x-intercept of the graph of x – 4y = 0 you can put 0 for y and solve for x. Your first two lines look good.

But x - 0 is not –x. It is just x. So your third line should be x = 4, meaning (4, 0) is on the graph.

By the way, if order was switched, 0 - x would be –x. Is that maybe what you were thinking when writing third line?

[u/CalRPCV]

As has been pointed out, a system of equations involves more than one equation. What you have written is confusing and could have a few different interpretations. I could make up a system of equations from it:

1. x - 4y = 4

2. -x = 4

In other words, these are two separate equations, not one derived from the other. If that is the case, then equation 1 would be a line with a slope of 1/4 that intersected the x axis at 4 because x - 4(0) = 4 means when y is zero, x is 4. The slope of the line can be seen on your graph. Or you can re-arrange the equation as y = (1/4)x - 1. The y intercept, where x is 0, is -1.

Then equation 2 is a vertical line crossing the x axis at - 4.

If you drew the graph for each equation then they would intersect at the point (-4, -2).

[u/DetentionSpan]

Do you have to graph this line?

y = mx + b ???

What are the two equations?

[u/JaxtonGoezHard]

yeah im pretty sure

[u/Deepbliss4]

No clue what’s even going on here tbh

[u/CalculadoraAlicia-ap]

Both parts are true, and keeping them separate helps:

1. The general rule: if you ever do get -x = 4, then yes, x = -4. Think of -x as (-1) times x, so divide (or multiply) both sides by -1: (-1)(-x) = (-1)(4), which gives x = -4.

2. In this specific work, though, you do not have -x. Starting from x - 4y = 4 and setting y = 0 for the x-intercept: x - 4(0) = 4, so x - 0 = 4, so x = 4. That gives the point (4, 0) on the graph. The minus sign belongs to the 4y term, not to x, so it disappears when y = 0.

[u/Broad-Raspberry-6296]

Think of it as multiplying -1 to both sides of the equation. So yes, -x * (-1) = 4 * (-1) will give you x=-4

[u/Plane_Tailor7168 → u/Broad-Raspberry-6296]

i think you missunderstood him (or im just an idiot)

[u/Plane_Tailor7168 → u/Plane_Tailor7168]

wait no im sorry but i think he messed up in the image bc it should just be x=4