Explanation
Correct answer: D.
Choice D is correct. Adding the two expressions yields . Because the pair of terms and and the pair of terms and each contain the same variable raised to the same power, they are like terms and can be combined as and , respectively. The sum of the given expressions therefore simplifies to .
Desmos solution:
Note: The regression fits a=7 and b=9, which give the displayed equivalent expression.
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect and may result from adding the coefficients and the exponents in the given expressions.
Choice B
Choice B is incorrect and may result from adding the exponents as well as the coefficients of the like terms in the given expressions.
Choice C
Choice C is incorrect and may result from multiplying, rather than adding, the coefficients of the like terms in the given expressions.