Study Guide and Review
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The formula to factor the difference of two squares is a^2-b^2=(a+b)(a-b).
(4a+sqrt(21)b)(4a-sqrt(21)b)
Look closely at the expression 16a^2-21b^2. It can be expressed as the difference of two perfect squares.
Write as a power
a^m b^m = (a b)^m
Distribute (4a-sqrt(21)b)
Distribute 4a
Distribute sqrt(21)b
Subtract term
After applying the Distributive Property and simplifying, the result is the same as the given expression. Therefore, we can be sure our solution is correct!