Skill: Check solutions by substitution

Explanation and Free Practice Resources

Substitution means replacing a variable in an equation with a proposed value, evaluating both sides according to the order of operations, and determining whether the resulting numerical statements are equal. This distinguishes a value that satisfies an equation from one that merely makes one side true and supports later reasoning about equivalent equations and algebraic solutions; the focus is on simple one-variable equations and does not include formal proof of identities, systems, or advanced symbolic verification.

Detailed Explanation: Check solutions by substitution

To check whether a proposed value solves an equation, substitute it for the variable.

  1. Replace every variable with the proposed value.
  2. Evaluate each side using the order of operations.
  3. Compare the two answers. If they are equal, the value is a solution.

Example: Check whether x=4x=4 is a solution to

2x+5=132x+5=13

Replace xx with 44:

2(4)+5=132(4)+5=13

Evaluate the left side:

8+5=138+5=13

Now compare both sides:

13=1313=13

The two sides are equal, so x=4x=4 is a solution to the equation.

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Verify a Solution to a Linear Equation - Single Equation to True or False


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