Use equations with unknown variables to rewrite expressions

The  exercise appears under the Algebra I Math Mission. This exercise practices substituting into expressions for several variables simultaneously.

Types of Problems
There is one type of problem in this exercise:


 * 1) Which one of these expressions is equivalent?: This problem provides an equation with one or more variables and an expression involving those variables. The student is expected to evaluate which other expression in the multiple choice list is also equivalent.Use equations with unknown variables to rewrite expressions.PNG

Strategies
An ability to visualize the expression and how it looks when distributed would assist with completing this exercise accurately and efficiently.
 * 1) On this exercise the coefficients on the equations are the same. Therefore the value of the instance of the variable in the expression is the coefficient times the value in the equation.
 * 2) On paper, the step-by-step process would be to factor a GCF out of the expression where appropriate, then substitute the value of the equation for it.

Real-life Applications

 * 1) Strategies like the ones needed for this exercise are common on standardizes tests and some math competitions such as AMC and AIME.