Simplify: (a + 3b)(a + 5b) - (a + 4b)^2 My steps: - parenthesis first, then exponent a^2 + 5ab + 3ab + 15b^2 - a^2 + 16b^2 - add/subtract like terms 31b^2 + 8ab The answer key given is -b^2. Where did I go wrong? Thanks.

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Originally Posted by shenton Simplify: (a + 3b)(a + 5b) - (a + 4b)^2 My steps: - parenthesis first, then exponent a^2 + 5ab + 3ab + 15b^2 - a^2 + 16b^2 - add/subtract like terms 31b^2 + 8ab The answer key given is -b^2. Where did I go wrong? Thanks. Hello, your 2nd line should read: a^2 + 5ab + 3ab + 15b^2 - (a^2 +8ab+ 16b^2) a^2 + 5ab + 3ab + 15b^2 - a^2 - 8ab- 16b^2 EB

Thanks for the help!

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