Answer:
a)
b)
Step-by-step explanation:
From the question we are told that
The Function

Generally the differentiation of function f(x) is mathematically solved as


Therefore

Generally critical point is given as



Generally the maximum and minimum x value for critical point is mathematically solved as

Where
Maximum value of x

Minimum value of x

Therefore interval of increase is mathematically given by


Therefore interval of decrease is mathematically given by

Generally the second differentiation of function f(x) is mathematically solved as

Generally the point of inflection is mathematically solved as


Therefore inflection points is given as


a)Generally the concave upward interval X is mathematically given as


b)Generally the concave downward interval Y is mathematically given as

I believe what the problem means is that the height of the child, if he/she grows in height, the mesurements are equal to 1 ft, 2 ft, 3 ft, 4 ft, etc only. and no decimals or fractions in between. it is also said that a human stops growing at the age of 20 naturally, hence with this increment, a child can grow incredibly very tall.
Multiply both sides of the second equation by 100 to get rid of the decimals:
0.05<em>n</em> + 0.10<em>d</em> = 1.50
==> 5<em>n</em> + 10<em>d</em> = 150
Multiply both sides of the first equation by -5:
<em>n</em> + <em>d</em> = 21
==> -5<em>n</em> - 5<em>d</em> = -105
Add the two equations together:
(5<em>n</em> + 10<em>d</em>) + (-5<em>n</em> - 5<em>d</em>) = 150 + (-105)
Notice that the terms containing <em>n</em> get eliminated and we can solve for <em>d</em> :
(5<em>n</em> - 5<em>n</em>) + (10<em>d</em> - 5<em>d</em>) = 150 - 105
5<em>d</em> = 45
<em>d</em> = 45/5 = 9
Plug this into either original equation to solve for <em>n</em>. Doing this with the first equation is easiest:
<em>n</em> + 9 = 21
<em>n</em> = 21 - 9 = 12
So Donna used 12 nickels and 9 dimes.
Thats How you go from slope to to standard form