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Algebra basics (ASL)

Course: Algebra basics (ASL) > Unit 2

Lesson 2: Substitution & evaluating expressions (ASL)
Math
Algebra basics (ASL)
Algebraic expressions (ASL)
Substitution & evaluating expressions (ASL)
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Evaluating expressions with two variables

Google Classroom
We've already evaluated expressions with one variable. Now it's time to do it with two variables.
Khan Academy video wrapper
Evaluating expressions with two variablesSee video transcript

How to evaluate an expression with two variables

Let's say we want to evaluate the expression 10, plus, 2, p, minus, 3, r. Well, first we need to know the values of p and r. For example, to evaluate the expression when start color #11accd, p, equals, 4, end color #11accd and start color #e07d10, r, equals, 5, end color #e07d10, we just replace start color #11accd, p, end color #11accd with start color #11accd, 4, end color #11accd and start color #e07d10, r, end color #e07d10 with start color #e07d10, 5, end color #e07d10:
empty space, 10, plus, 2, start color #11accd, p, end color #11accd, minus, 3, start color #e07d10, r, end color #e07d10
equals, 10, plus, 2, dot, start color #11accd, 4, end color #11accd, minus, 3, dot, start color #e07d10, 5, end color #e07d10
equals, 10, plus, 8, minus, 15
equals, 3
So, the expression 10, plus, 2, p, minus, 3, r equals 3 when p, equals, 4 and r, equals, 5.

Now, let's practice

Problem 1
  • Current
Evaluate 6, a, plus, 4, b, minus, 6 when a, equals, 1 and b, equals, 3.
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3, slash, 5
  • a simplified improper fraction, like 7, slash, 4
  • a mixed number, like 1, space, 3, slash, 4
  • an exact decimal, like 0, point, 75
  • a multiple of pi, like 12, space, start text, p, i, end text or 2, slash, 3, space, start text, p, i, end text