How Do You Substitute Values Into An Algebraic Expression?
Much work in mathematics requires us to substitute values into an algebraic expression. This is especially true when using formulas to calculate quantities such as area and volume. It really isn’t difficult, but as with anything it can be a tad confusing until you get the hang of it. Look at the examples below that show how to substitute values into some different algebraic expressions. Consider the following problem: Evaluate the algebraic expression x + 2y for x = 3 and y = 4. This just means to re-write the expression but substitute the number 3 for the x and the number 4 for the y, then do the computation. It looks like this: x + 2y 3 + 2(4) 3 + 8 = 11So the algebraic expression x + 2y, when evaluated for x = 3 and y = 4, equals 11. Look at another example. Substitute 2 for x and 5 for y in the algebraic expression 4x – 3y. Just as we did in Step 1, re-write the expression, substitute the numerical values for x and y, and do the computation. Here it is: 4x – 3y 4(2) – 3(5) 8 – 15 =
