We can find the length of DE using the Pythagorean Theorem:

2 answers:

8 0

The answer is

C) DE = (4 - 1)2 + (1 - 3)2

rewriten

DE = sqrt (4 - 1)^2 + (1 - 3)^2

prohojiy [21]3 years ago

6 0

What's the difference between A) and C)??
There should be an E) because the correct answer would be in either of these forms:
${DE}^{2} = {(4 - 1)}^{2} + {(1 - 3)}^{2} \: \: or \\ DE = \sqrt{( {3}^{2} + {2}^{2} )} \: \: or \\ {DE}^{2} = {(4 - 1)}^{2} + {(3 - 1)}^{2}$

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The function f(x) = –x2 + 20x – 75 models the profit from one customer, in dollars, a shop makes for printing photos, where x is

trasher [3.6K]

The function is graphed as shown below

Part A:

We use the formula $- \frac{b}{2a}$ to find the vertex of the function. A quadratic function of the form of $a x^{2} +bx+c$ and equating this form to the given function $- x^{2} +20x-75$ , we have
$b=20$ and $a=-1$ .

Substituting $a$ and $b$ into the vertex formula, we have
$x=- \frac{20}{2(-1)}=10$ , as shown in the graph

This calculation means that the highest profit is achieved when the number of photo printed equals to ten photos

Part B:

We can find solution to this equation by factorising

$- x^{2} +20x-75=0$
$-( x^{2} -20x+75)=0$
$x^{2} -20x+75=0$
$(x-5)(x-15)=0$
$x=5$ and $x=15$ , as shown in the graph

The two values means that the company makes no profit when they either produce 5 or 15 photos