Question

1. Writing an equation for an exponential function by

Answer 1

Answer: 1) $t(n)=0.6(2)^n$

2) $f(x)=10(5)^x$

Step-by-step explanation:

1) Let the function that shows the thickness of the paper after n folds,

$t(n) = ab^n$         ---------(1)

Since, According to the question,

Initially the thickness of the paper = 0.6

That is, at n = 0, t(0) = 0.6

By equation (1),

$0.6 = a(b)^0\implies 0.6 = a$

Hence the function that shows the given situation,

$t(n) = 0.6 b^n$       -----------(2)

Again when we fold the paper the thickness of the paper will be doubled.

Thus, at n = 1, t(1) = 1.2

By equation (2),

$1.2 = 0.6 b^1\implies 2 = b$

Thus, the complete function is,

$t(n) = 0.6 (2)^n$    

2) Let the function that is passing through the points (-2, 2/5) and (-1,2),

$f(x) = ab^x$         ---------(1)

For f(x) = 2, x = -1

By equation (1),

$2= ab^{-1}$       ---------(2)

Also, For f(x) = 2/5, x = -2

Again, By equation (1),

$\frac{2}{5}= a(b)^{-2}$

$\implies \frac{2}{5}=ab^{-1}b^{-1}=2b^{-1}$

$\implies \frac{2}{5}=\frac{2}{b}$

$\implies 2b=10$

$\implies b = 5$

By substituting this value in equation (2),

We get, a = 10

Hence, from equation (1), the function that is passing through the points (-2, 2/5) and (-1,2),

$f(x) = 10(5)^x$