If you start with a 12x16 rectangle and cut square with side length x, when you bend the sides you'll have an inner rectangle with sides $12-2x$ and $16-2x$ , and a height of x.

So, the volume will be given by the product of the dimensions, i.e.

$(12-2x)(16-2x)x = 4x^3-56x^2+192x$

The derivative of this function is

$12x^2-112x+192$

and it equals zero if and only if

$12x^2-112x+192=0 \iff x = \dfrac{14\pm 2\sqrt{13}}{3}$

If we evaluate the volume function at these points, we have

$f\left(\dfrac{14-2\sqrt{13}}{3}\right) = \dfrac{64}{27}(35+13\sqrt{13})> f\left(\dfrac{14-2\sqrt{13}}{3}\right) = -\dfrac{64}{27}(13\sqrt{13}-35)$

So, the maximum volume is given if you cut a square with side length

$x=\dfrac{14-2\sqrt{13}}{3}\approx 2.7$

5 0

3 years ago

What is the LCM and GCF for the numbers 81 and 99

artcher [175]

9 is the LCM, and the GCF is 27

8 0

3 years ago

Read 2 more answers

A radioactive element has a half-life of 5,750 years. Archeologists determined a relic had lost 25.5% of this element at the tim

Dmitry [639]

Answer:

2441.95 years

Step-by-step explanation:

We can model this exponencial function as:

P = Po * (1+r)^(t/n)

Where P is the final value, Po is the inicial value, r is the rate, t is the time and n is the period of half-life.

In this case, we have that P/Po = 100% - 25.5% = 74.5% = 0.745, r = -0.5 and n = 5750, so we have that:

0.745 = (1 - 0.5)^(t/5750)

Step 1: log in both sides:

log(0.745) = (t/5750) * log(0.5)

Step 2: isolate t

t = 5750*log(0.745)/log(0.5) = 2441.95 years

3 0

3 years ago