Answer :
Answer:
As x increases, the rate of change of g exceeds the rate of change of f.
Step-by-step explanation:
Given
[tex]f(x) = 90x^2 + 180x + 92[/tex]
[tex]\begin{array}{ccccccc}x & {0} & {1} & {2} & {3} & {4} & {5} & f(x) & {92} & {362} & {812} & {1442} & {2252} & {3242} \ \end{array}[/tex]
[tex]g(x) = 6^x[/tex]
[tex]\begin{array}{ccccccc}x & {0} & {1} & {2} & {3} & {4} & {5} & g(x) & {1} & {6} & {36} & {216} & {1296} & {7776} \ \end{array}[/tex]
Required
Which of the options is true?
A. At [tex]x \approx 4.39[/tex], f(x) has the same rate of change as g(x)
Rate of change is calculated as:
[tex]m = \frac{y_2 - y_1}{x_2 - x_1}[/tex]
For f(x)
[tex]f(x) = 90x^2 + 180x + 92[/tex]
[tex]f(4.39) = 90*4.39^2 + 180*4.39 + 92 = 2616.689[/tex]
So, the rate of change is:
[tex]m = \frac{2616.689}{4.39} = 596.06[/tex]
For g(x)
[tex]g(x) = 6^x[/tex]
[tex]g(4.39) = 6^{4.39} = 2606.66[/tex]
So, the rate of change is:
[tex]m = \frac{2606.66}{4.39} = 593.77[/tex]
The rate of change of both functions are not equal at x = 4.39. Hence, (a) is false.
B. Rate of change of g(x) is greater than f(x) with increment in x
Using the formula in (a), we have:
[tex]\begin{array}{ccccccc}x & {0} & {1} & {2} & {3} & {4} & {5} & f(x) & {92} & {362} & {812} & {1442} & {2252} & {3242} & m &\infty & 362 & 406 & 480 & 563 &648.4\ \end{array}[/tex]
[tex]\begin{array}{ccccccc}x & {0} & {1} & {2} & {3} & {4} & {5} & g(x) & {1} & {6} & {36} & {216} & {1296} & {7776} & m & \infty & 6 & 18 & 72 & 324 & 1555 \ \end{array}[/tex]
From x = 1 to 4, the rate of change of f is greater than the rate of g.
However, from x = 5, the rate of change of g is greater than the rate of f.
This means that (b) is true.
The above table further shows that (c) and (d) are false.