How do you solve for a formula?

Question

the question says the formula for the perimeter of a rectangle is P=2l + 2w solve the formula for w. but how do you do that if you dont have numbers for w?

Answer 1

When you have a problem that tells you to solve for a variable, your W, it is asking you to isolate that variable. To isolate W in P= 2l + 2w you could...

1. factor out a two -> P = 2(l + w)

2. divide by that two -> P / 2 = l + w

3. then isolate the w by subtracting L from both sides -> (P / 2) - l = w

OR you could...

1. take away 2l from both sides which you give you -> P - 2l = 2w

2. divide both sides by 2, thus isolating the w -> (P - 2l) / 2 = w

And there you go, you have solved for w in two different ways, => (P - 2l) / 2 = w, and (P / 2) - l = w. both are equal and mean the same thing.

Hope this helps~!!!  

Answer 2

Actually all that you have to do for this question is isolate the variable.

So, try to follow these simple steps:

P=2L + 2w

P - 2L =2w

(P - 2L) / 2 = w

w = P/2 - L

I tried to make it as simple as I could, but if you still dont understand feel free to ask me to go more in depth.

Answer 3

Just solve for the variable just like you would any other variable:

P = 2l + 2w (divide both sides by 2)

P/2 = l + w (subtract l from both sides)

P/2 - l = w

w = P/2 - l <===ANSWER

Answer 4

It sounds like this is your first encounter with algebraic identities. Try imagining the variables P,l, and w, as numbers. The process for solving for w is very simple. First, subtract the number (2*l) from both sides. This will leave P - 2l = 2l + 2w - 2l. On the right side, the 2l and the -2l cancel each other out, leaving P - 2l = 2w. Now divide both sides by two, the right side should cancel leaving just w, and the left side should be (P - 2l) / 2 = w.

P = 2l + 2w

P - 2l = 2w

(P - 2l) / 2 = w

(P / 2) - l = w