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Grade 9–10 · Concept lesson

Exponential Expressions Examples

About this video

Worked examples applying the exponent laws to simplify expressions — multiplying, dividing and raising powers to powers.

What it covers

  • Rule 1: multiplying the same base — add the exponents
  • Rule 2: dividing the same base — subtract the exponents
  • Rule 3: change numbers to the same base, in brackets (25 = 5²)
  • Rule 4: an exponent outside a bracket multiplies every exponent inside
  • Negative exponents move to the denominator; a zero exponent gives 1
  • A minus between two terms: take out a common factor

Extra worked examples

✍️ Extra example: simplify (2a²b)³ · ab⁴ ÷ 4a⁵b³
  1. 1
    (2a²b)³ = 2³a⁶b³ = 8a⁶b³
    Rule 4: the 3 multiplies every exponent inside — the 2 as well.
  2. 2
    8a⁶b³ · ab⁴ = 8a⁷b⁷
    Rule 1: a has an exponent of 1, so 6 + 1 = 7; and 3 + 4 = 7.
  3. 3
    8a⁷b⁷ ÷ 4a⁵b³ = 2a²b⁴
    Numbers first (8 ÷ 4 = 2), then Rule 2: subtract the exponents.
✍️ Extra example: simplify (5n + 1 − 5n)/5n
  1. 1
    (5n(5 − 1))/5n
    A minus between the terms — no rule applies across it, so take out the common factor 5ⁿ.
  2. 2
    = 4
    Now 5ⁿ is a factor top and bottom and cancels.

Exercises to try

Work each one out, then click to reveal the answer.

  1. 1
    Simplify a⁵ · a³.
    Show answer ▾
    a⁸ (Rule 1)
  2. 2
    Simplify (y²)⁴.
    Show answer ▾
    y⁸ (Rule 4)
  3. 3
    Simplify 12x⁵y²/4x²y⁵ and leave positive exponents.
    Show answer ▾
    3x³y−3 = 3x³/y³
  4. 4
    Simplify (25x · 5)/(52x + 1).
    Show answer ▾
    ((5²)x · 51)/(52x + 1) = (52x + 1)/(52x + 1) = 1
  5. 5
    Simplify (3n + 2 − 3n)/(8 · 3n).
    Show answer ▾
    (3n(9 − 1))/(8 · 3n) = 1

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