HELP PLEASe!!!!!?

Question

Suppose that N=√x +2 models the number of cases of an infection, in millions, of a disease x years from now.

In approximately how many years will there be 7 million cases?


Can someone show me how to come up with the answer I think it is 25 but I do not know how to show the work for this.....

Thank you to all

Answer 1

Just plug in 7 for N. N is the number of cases (in millions) as a function of years.

7 = root(x) + 2
subtract 2 from each side
5 = root(x)

Now, keep in mind, if you're taking the square root of something, you're raising it to the 1/2 power.

So, having 5 = x^[1/2], to solve for x, you need to raise both sides to the second power:

5^2 = (x^[1/2])^2
25 = x

So, you were right. Remember, raising a power to another power simply means multiplying the two powers. 1/2*2 = 1.

Answer 2

Assuming that x is the only thing under the radical (i.e., you mean "(√x) + 2" and not "√(x + 2)"):

√x +2 = 7
√x = 5
x = 5^2
x = 25

Otherwise, if you mean √(x + 2):

√(x + 2) = 7
(x + 2) = 7^2
x = 49 - 2
x = 47

Answer 3

7 = sqrt(x) + 2
5 = sqrt(x) {subtract 2 from both sides}
25 = x {square both sides}