In the newspaper ,mr. shields read that the poplulation of jefferson county was decreasing at a rate of 20% every year. is this exponential or linear function ? why ? or why not?

Exponential.

Step-by-step explanation:

The population function looks like P = Po (1 - 0.20)^t, or Po (0.80)^t.  Because the common ratio, 0.80, is between 0 and 1, this equation is appropriate for an exponentially decreasing decreating function.

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.

your answer is  

a.

5

step-by-step explanation: