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Multiply radicals

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Learn it Multiply the outside numbers together and the inside numbers together: $a\sqrt{b} \times c\sqrt{d} = ac\sqrt{bd}$. For brackets, multiply every term by every term (FOIL).

Example: $(2 + \sqrt{3})(4 - \sqrt{3})$

  1. First: $2 \times 4 = 8$.
  2. Outer + inner: $-2\sqrt{3} + 4\sqrt{3} = 2\sqrt{3}$.
  3. Last: $\sqrt{3} \times (-\sqrt{3}) = -3$.
  4. Total: $5 + 2\sqrt{3}$.

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