Algebra help....?

Question

how do i put 2x-5y=20 in function form?? please help me!

Answer 1

I think this is asking you to express one variable in terms of the other.  In other words, one variable (x or y) is a function of (depends on) the other (y or x).

In your example, y depends upon x to tell it what it should be so that whatever x is, twice x's value less 5 times y's value is 20.

We can rearrange the equation to say that

y = (20 - 2x)/(-5)

Equally validly, we could assume that x is the dependent variable, in which case we can say that

x = (20 + 5y)/2

In other words, x depends on y to assume a value and whatever y chooses to be, x will be half of 20 more than 5 times y's value.

Your choice it to pick a dependent variable.  Neither one is right and neither is wrong.   Whichever you choose, you need to rearrange the equation so that it (the dependent variable) is expressed in terms of the independent one.

If you need more help ,edit your question and I'll get back to you.

Answer 2

Function form is

y = mx + b

where m and b are coefficients.

You need to convert 2x - 5y = 20 to that form.

Steps:

1) Get the "x" term to the opposite side of the equation from the "y" term.  You want the "y" term by itself.

On one side you have 2x-5y and on the other side you have 20.  If you subtract 2x from the 2x-5y you get (2x-5y)-2x.  This results in 2x-2x-5y and further to -5y.  Because you must do the same thing to both sides, subtract 2x from 20 and you get 20-2x.

Result:  -5y = 20-2x

2) Divide both sides of the equation by the coefficient of the "y" term.  This coefficient may be negative or positive, so make sure you divide by the exact coefficient.

The coefficient of the "y" term is -5.  Dividing both side by -5 gives

-5y/(-5) = 20/(-5) - 2x/(-5)

this simplifies to

y = -4 + (2/5)x

3) Rearrange to the y = mx + b form.

y = -4 + (2/5)x

Answer: y = (2/5)x - 4