Answer:
1. x< 3
2. x>12
have a great day :)
Step-by-step explanation:
![c^2](https://tex.z-dn.net/?f=c%5E2)
![2c^2 + 13c +21 \\4c^2 + 13(2)c + 42\\(2c + 6)(2c+7)\\(c+3)(2c+7)](https://tex.z-dn.net/?f=2c%5E2%20%2B%2013c%20%2B21%20%5C%5C4c%5E2%20%2B%2013%282%29c%20%2B%2042%5C%5C%282c%20%2B%206%29%282c%2B7%29%5C%5C%28c%2B3%29%282c%2B7%29)
This is a way to factoring trinomials (there exist different equivalent methods).
Multiply the trinomial but the term accompanying
. This is the second line. Then, you could take the square of the
, ant try to create a factor () () that will correspond to the expression in the second line. That is, we want ![4c^2 + 13(2) c + 42 = (2c + ?) (2c + ?)](https://tex.z-dn.net/?f=4c%5E2%20%2B%2013%282%29%20c%20%2B%2042%20%3D%20%282c%20%2B%20%3F%29%20%282c%20%2B%20%3F%29)
In ? we put the corresponding numbers that, if we multiply them we will obtain 42, and if we add them we will obtain 13. This numbers are 6 and 7. Then, we have ![(2c + 6) (2c +7)](https://tex.z-dn.net/?f=%282c%20%2B%206%29%20%282c%20%2B7%29)
The last step is divide by the number that we multipy in the first step.
A percentage is equivalent to a fraction, a percentage is out of 100 therefore the fraction for this can be 28/100, as a decimal this would be .28. Therefore to solve this problem you would set up the problem as, 942 x .28= 263.76, you then take that number and subtract it from the original price of the tv, and you get the final price, of $678.24.
I'm not sure what your variables are, but I will try task 3 with you.
y=$500(in billions)
x= the number of years that have passed since 2009
percentage of decrease: 1 - % =
so your formula will look like this: y(1 - %)^x