78.8 rounded to the nearest tenths is 78.8
We can not round it to the tenths because it already is rounded to the tenths.
H(x) = 1/4x would be the inverse
The first thing that he has to do is take that "minus" sign through the parentheses containing the second polynomial. Some students find it helpful to put a " 1 " in front of the parentheses, to help them keep track of the minus sign. Here's what the subtraction looks like, when working horizontally/
This is the diference of 2 perfect squares. 4 is a perfect square, x^2 is a perfect square, and 25 is a perfect square. The pattern for this is (ax + b)(ax - b). Our a is 2 since 2*2 = 4, and our b is 5 since 5*5 = 25. So your factors are (2a+5)(2a-5), choice C.
