5. Formulas and Literal Equations

It is very common in science and engineering to have a formula that needs re-arranging so that a variable that is originally on the right hand side becomes the subject of the formula, on the left.

In this section, we need to find an expression (involving letters and numbers) which is equal to a particular given letter. [Hence "literal" equation].

This is an important skill - you'll use it all the time in math and science (and engineering, too).

We simply solve the equation like we did in the previous Solving Equations section, by balancing both sides.

Example 1

We recall the area of a rectangle with width w and height h.

A = w × h

formula for area of a rectangle, A = wh

Express the formula in terms of the height.

Example 2

The area of a circle is given by

A = π r2

Solve for r.

Example 3

The formula for the area of a trapezoid is given by:

`A=h/2(x_1+x_2)`

where h is the height of the trapezoid and x1, x2 are the lengths of the parallel sides.

Solve the formula for x1.

Example 4

The pressure in an airtight container is given by the following formula. Solve for P1:

P = 0.05(P2 P1)

Didn't find what you are looking for on this page? Try search:

Online Algebra Solver

This algebra solver can solve a wide range of math problems. (Please be patient while it loads.)

Ready for a break?

 

Play a math game.

(Well, not really a math game, but each game was made using math...)

The IntMath Newsletter

Sign up for the free IntMath Newsletter. Get math study tips, information, news and updates each fortnight. Join thousands of satisfied students, teachers and parents!

Given name: * required

Family name:

email: * required

See the Interactive Mathematics spam guarantee.

Share IntMath!

Short URL for this Page

Save typing! You can use this URL to reach this page:

intmath.com/formlit

Algebra Lessons on DVD

 

Easy to understand algebra lessons on DVD. See samples before you commit.

More info: Algebra videos

Loading...
Loading...