Solving Literal Equations - Problem 1 10,274 views

Teacher/Instructor Alissa Fong
Alissa Fong

MA, Stanford University
Teaching in the San Francisco Bay Area

Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts

When solving literal equations that involve solving for a variable when there is more than one variable, use the same rules you would with any single variable equation. The goal is to "undo" what is being done to the variable that you must solve for. Use inverse operations to eliminate all other variables and numbers on the same side of the equal sign.

This exact problem is really often assigned to Math students and I know because I'm a Math teacher and I assign this one. The area of a triangle is a equals base times height divided by 2, solve for h.

Okay so this equation is kind of intimidating because there's only one number, I only have that 2 but I can still get h all by itself using what I know about solving. I want to undo whatever is being done to h. For example right now h is being divided by 2 so I'm going to do the opposite of dividing which is multiplying, multiply by 2, multiply by 2 so now I'm going to have 2a or 2 times the area, is equal to base times height. I'm almost done. They asked me to get h all by itself and it's almost by itself, h right now is being multiplied by b.

So to undo the multiplying I'm going to divide both sides by b and this is my final answer 2a divided by b. Don't forget that this is actually applicable to Math problems and areas of triangles. These aren't just random letters. What this tells me is that if I had to find the height of a triangle I would do 2 times the area and then divide by the length of the base. That would give me the length of the height. It's a pretty useful technique because you can find any one of these letters if you know the other two.