One question at a time, please. I will focus on #16 and ignore #18.
slope: 3/4 line passes thru (-8,2)
Write out y = mx + b. Subst. 2 for y. Subst. -8 for x Subst. (3/4) for m:
2 = (3/4)(-8) + b. Find b. 2 = -6 + b => b = 8
So your equation is y = (3/4)x + 8. Please, use ( ) around those fractions!
The statement "unit cubes with side lengths of 1/2 foot are added to fill the prism with no space remaining" is useless information so you can disregard that. All you need to know to calculate the volume is the length, width, and height.
Volume = length x width x height
Volume = (5/2) x 3 x 11/2
Volume = 15/2 x 11/2
Volume = 165/4
Volume = 41.25 ft cubed
cos4x = cos2x
We know that:
cos2x = 1-2cos^2 x
==> cos4x = 1-2cos^2 (2x)
Now substitute:
==> 1-2cos^2 (2x) = cos2x
==> 2cos^2 (2x) + cos2x - 1 = 0
Now factor:
==> (2cos2x -1)(cos2x + 1) = 0
==> 2cos2x -1 = 0 ==> cos2x =1/2 ==> 2x= pi/3
==> x1= pi/6 , 7pi/6
==> x1= pi/6 + 2npi
==> x2= 7pi/6 + 2npi
==> cos2x = -1 ==> 2x= pi ==> x3 = pi/2 + 2npi.
<span>==> x= { pi/6+2npi, 7pi/6+2npi, pi/2+2npi}</span>
Answer: 14x^7
You add the coefficients (numbers to the left of the variable terms) to get 6+8 = 14 which is the coefficient of the final answer. The x^7 stays the same. It's like saying "we have 6 apples added to 8 apples, so there are 14 apples overall". Replace "apples" with "x^7" and it's the same idea.
