The answer is D hope this helps :]
Answer: 6.4
Step-by-step explanation: If rounding to one decimal place, your answer would be 6.4.
49.6 divided by 7.8 = 6.35897435...
Now, we see that after the 3 (The first decimal place) there is a five. Because we are rounding to the first decimal place the second decimal place will tell us to round up or down. In this case because it's a five, we would round up.
(x + 2)(5x^2 + x - 4) =
x(5x^2 + x - 4) + 2(5x^2 + x - 4) =
5x^3 + x^2 - 4x + 10x^2 + 2x - 8 =
5x^3 + 11x^2 - 2x - 8 <===
.87 is correct you can always check your work with an online calculator. :)