Answer:
Step-by-step explanation:
Given: 
To convert: the given sum into product
Solution:
Use formula: 
![cosx + cos3x + cos5x + cos7x=2\cos \left ( \frac{x+3x}{2} \right )\cos \left ( \frac{x-3x}{2} \right )+2\cos \left ( \frac{5x+7x}{2} \right )\cos \left ( \frac{5x-7x}{2} \right )\\=2\cos (2x)\cos (-x)+2\cos (6x)\cos (-x)\\=2\cos (2x)\cos (x)+2\cos (6x)\cos (x)\\=2\cos x\left [ \cos (2x)+\cos (6x) \right ]](https://tex.z-dn.net/?f=cosx%20%2B%20cos3x%20%2B%20cos5x%20%2B%20cos7x%3D2%5Ccos%20%5Cleft%20%28%20%5Cfrac%7Bx%2B3x%7D%7B2%7D%20%5Cright%20%29%5Ccos%20%5Cleft%20%28%20%5Cfrac%7Bx-3x%7D%7B2%7D%20%5Cright%20%29%2B2%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B5x%2B7x%7D%7B2%7D%20%5Cright%20%29%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B5x-7x%7D%7B2%7D%20%5Cright%20%29%5C%5C%3D2%5Ccos%20%282x%29%5Ccos%20%28-x%29%2B2%5Ccos%20%286x%29%5Ccos%20%28-x%29%5C%5C%3D2%5Ccos%20%282x%29%5Ccos%20%28x%29%2B2%5Ccos%20%286x%29%5Ccos%20%28x%29%5C%5C%3D2%5Ccos%20x%5Cleft%20%5B%20%5Ccos%20%282x%29%2B%5Ccos%20%286x%29%20%5Cright%20%5D)
![cosx + cos3x + cos5x + cos7x=2\cos \left ( \frac{x+3x}{2} \right )\cos \left ( \frac{x-3x}{2} \right )+2\cos \left ( \frac{5x+7x}{2} \right )\cos \left ( \frac{5x-7x}{2} \right )\\=2\cos x\left [ \cos (2x)+\cos (6x) \right ]\\=2\cos x\left [2 \cos \left ( \frac{2x+6x}{2} \right )\cos \left ( \frac{2x-6x}{2} \right ) \right ]\\=2\cos x\left [ 2\cos (4x) \cos (-2x) \right ]\\=4\cos x\cos (4x)\cos (2x)](https://tex.z-dn.net/?f=cosx%20%2B%20cos3x%20%2B%20cos5x%20%2B%20cos7x%3D2%5Ccos%20%5Cleft%20%28%20%5Cfrac%7Bx%2B3x%7D%7B2%7D%20%5Cright%20%29%5Ccos%20%5Cleft%20%28%20%5Cfrac%7Bx-3x%7D%7B2%7D%20%5Cright%20%29%2B2%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B5x%2B7x%7D%7B2%7D%20%5Cright%20%29%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B5x-7x%7D%7B2%7D%20%5Cright%20%29%5C%5C%3D2%5Ccos%20x%5Cleft%20%5B%20%5Ccos%20%282x%29%2B%5Ccos%20%286x%29%20%5Cright%20%5D%5C%5C%3D2%5Ccos%20x%5Cleft%20%5B2%20%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B2x%2B6x%7D%7B2%7D%20%5Cright%20%29%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B2x-6x%7D%7B2%7D%20%5Cright%20%29%20%5Cright%20%5D%5C%5C%3D2%5Ccos%20x%5Cleft%20%5B%202%5Ccos%20%284x%29%20%5Ccos%20%28-2x%29%20%5Cright%20%5D%5C%5C%3D4%5Ccos%20x%5Ccos%20%284x%29%5Ccos%20%282x%29)
If x = # of quarters, then, the # of dimes will be equal to 2x. The total value (z) would be equal to:
z = 0.25x + 0.10(2x)
Then, since you switch the quarters and the dimes, and you have a new total, the resulting equation will be:
1.2 + z = 0.25(2x) + 0.10(x)
Plug in the values you know:
1.2 + (0.25x + 0.10(2x)) = 0.25(2x) + 0.10(x)
Solve for x:
1.2 + (0.25x + 0.20x) = 0.50x + 0.10x
1.2 + 0.45x = 0.60x
1.2 = 0.15x
x = 1.2/0.15 = 8
This means that there are 8 Quarters in her bag right now. So, the amount of dimes is just 2x which is 16. So your answer will be:
She has 8 Quarters and 16 Dimes in her bag right now. Or, $3.60.
If this doesn't make sense, then tell me. I have some resources where I got the answer from to put it into simplest terms. I have the website if you want.
Answer:
y+3=-3(x+1)
Step-by-step explanation:
y-y1=m(x-x1)
m=-3
y-(-3)=-3(x-(-1))
y+3=-3(x+1)
