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Question 171479: 3. (7a^4 + 8ab + b^2) + (-5a^4 - 8ab - 4b^2)
Answer by colliefan(242)   (Show Source):
You can put this solution on YOUR website! (7a^4 + 8ab + b^2) + (-5a^4 - 8ab - 4b^2)
You can combine terms only if they have the same variables and those variables are raised to the same power. For example, a term with a cannot be combined with one that has the variable b or even with a^4, only with another term that has the variable a. A term with ab can only be combined with another term with ab.
To solve the above, group the terms so that the terms with like variables are together. Since there is a + before the second set of parentheses, all the terms in those parentheses keep the sign they have now. The first set of parentheses also can be dropped, because they do not change the meaning of the expression written without them. So:
(7a^4 + 8ab + b^2) + (-5a^4 - 8ab - 4b^2)
7a^4 + 8ab + b^2 + -5a^4 - 8ab - 4b^2
Regroup: 7a^4 + -5a^4 + 8ab - 8ab + b^2 - 4b^2
Combine terms: (7 + -5)a^4 + (8-8)ab + (1-4)b^2
Simplify: 2a^4 + 0ab + -3b^2
Simplify: 2a^4 - 3b^2
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