MYP 3 Mathematics · Number

Laws of exponents — all laws

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  1. Question 1

    Which expression is the correct simplification of ?
    No clue? Show me the answer
    Correct answerCorrect!Incorrect
    A

    Step-by-step walkthrough

    Choose a solution method

    Method #1Direct Approach

    Step 1: Identify the law to apply

    We are multiplying two powers with the same base (5). This calls for the Product Rule: .

    Step 2: Add the exponents

    Keep the base as 5 and add the exponents:

    Step 3: State the answer

    The simplified expression is . The base stays as 5 — it does not get multiplied.

    Method #2Process of Elimination

    Step 1: Identify what is being asked

    We need to simplify using exponent laws. The key question is: what happens to the base and exponents when multiplying same-base powers?

    Step 2: Eliminate $5^{18}$

    The option would result from multiplying the exponents (). That rule applies to a power of a power like , not a product. So this is wrong.

    Step 3: Eliminate $25^9$

    The option multiplies both the base () and adds the exponents. This is a double error — the base must stay as 5, not change to 25.

    Step 4: Eliminate $5^{15}$

    The option does not match any standard rule here. , not 15. This value has no logical basis.

    Step 5: Select the correct answer

    The correct answer is , found by applying the product rule: .

  2. Question 2

    A student simplifies and gets . Which exponent law did the student use?
    No clue? Show me the answer
    Correct answerCorrect!Incorrect
    AQuotient Rule: subtract the exponents

    Step-by-step walkthrough

    Choose a solution method

    Method #1Direct Approach

    Step 1: Identify the operation

    The expression is a division (a fraction) of two powers with the same base. This matches the Quotient Rule.

    Step 2: Apply the Quotient Rule

    The Quotient Rule states . So:

    Step 3: Confirm the law used

    The student subtracted the exponents (), which is exactly the Quotient Rule.

    Method #2Process of Elimination

    Step 1: Identify what is being asked

    We need to identify which law produces the result from .

    Step 2: Eliminate the Product Rule

    The Product Rule applies to multiplication, giving . Here we have division, not multiplication, so this law does not apply.

    Step 3: Eliminate the Power of a Power Rule

    The Power of a Power Rule applies to expressions like , where a power is raised to another power. This is a division expression, so that rule is irrelevant.

    Step 4: Eliminate the Zero Exponent Rule

    The Zero Exponent Rule tells us that . Since the result is , not 1, this rule is not what was used.

    Step 5: Select the correct answer

    The correct law is the Quotient Rule: , giving .

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