Literal equation solver: solve a formula for any variable
Treat every other letter as a number and isolate the one you want.
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What counts as a literal equation?
A literal equation is an equation with several letters, which usually means a formula. Solving it “for” a variable means rearranging it so that variable stands alone.
The moves are exactly the same as with numbers. The only difference is that the answer is an expression rather than a number. After solving, pick another letter in the “Solve for” menu to rearrange the same formula a different way.
How to rearrange a formula
- Decide which variable you want alone and treat every other letter as a constant.
- Expand brackets that contain that variable.
- Move every term containing the variable to one side and the rest to the other.
- If more than one term contains it, factor the variable out.
- Divide by whatever is multiplying it, and note that divisor can’t be zero.
Frequently asked questions
What is a literal equation?
Any equation with two or more variables, such as d = rt or 2x + 3y = 12. Formulas in science and finance are literal equations.
How do I solve for a variable that appears twice?
Collect both terms on one side and factor the variable out. For example, ax + bx = c becomes x(a + b) = c, so x = c/(a + b).
Why does the answer say “valid when … ≠ 0”?
Because the last step divides by an expression, and division by zero is undefined. The rearranged formula only works when that expression is not zero.