4x2+28x+49=0(2x+7)(2x+7)=0
2x+7=0 or 2x+7=0
x=
Answer: 21?
Step-by-step explanation: if the ratio is 7:5 and its now x:15 and 15 divided by 5 is three so you have to multiply 7 by three to.
65.8 + 13.4 = 79 .2. So the answer is c
Answer:
100.7%
Step-by-step explanation:
Since the interest is compounded quarterly, and there are 4 quarters per year, that would leave us with 32 quarters total where interest is acquired. Now, we need to find the interest rate, that would be required in order to end up with 420 dollars after 32 quarters.
We can setup a formula using our period of time and the money he invested into the bank:
![340(x)^{32}=420](https://tex.z-dn.net/?f=340%28x%29%5E%7B32%7D%3D420)
We can divide 340 from both sides, and simplify the right side to 21 divided by 17:
![x^{32}=\frac{21}{17}](https://tex.z-dn.net/?f=x%5E%7B32%7D%3D%5Cfrac%7B21%7D%7B17%7D)
Taking the 32th root of 21/17 is equal to 1.00662, which is equal to 100.0662%. To the nearest tenth of a percent, this is equal to 100.7%.
Let t be time and r be rate, then if time varies inversely with the rate, the equation is
![t= \frac{k}{r}](https://tex.z-dn.net/?f=t%3D%20%5Cfrac%7Bk%7D%7Br%7D%20)
. If it takes 5 hours to drive a fixed distance at a rate of 80, we can sub those values in to solve for the constant of variation, k.
![5= \frac{k}{80}](https://tex.z-dn.net/?f=5%3D%20%5Cfrac%7Bk%7D%7B80%7D%20)
. Solve for k by multiplying 5 and 80 to get that k = 400. Now let's find a new time t when r is a rate of 70. We will use that k value to do this:
![t= \frac{400}{70}](https://tex.z-dn.net/?f=t%3D%20%5Cfrac%7B400%7D%7B70%7D%20)
and find that it will take 20 hours to drive the distance at 70 mph when it takes 5 hours to drive the distance at 80 mph. Makes sense that it takes longer to drive a fixed distance when you are going slower.