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3 years ago

TEACHER QUESTION

Mathematics

2 answers:

DedPeter [7]3 years ago

5 0

Answer: 62.33 57.67

Step-by-step explanation:

Schach [20]3 years ago

3 0

Answer:

Step-by-step explanation:

Year 2004: 62.33

Year 2013: 57.67

2013-2004 = 9

57.67-62.33 =-4.66

-4.66/9 = -0.517777778 which is the average rate of change

Here the the avg. rate of change means that on average, the change in rainfall every year is -0.517777... inches

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The area of a tabletop is 48 square feet. the length is 3 times the width.if the dimensions are whole numbers, what is the width

posledela

(4 feet wide), 12 feet in length. 4*3=12 4*12=48

7 0

3 years ago

Prove or disprove (from i=0 to n) sum([2i]^4) <= (4n)^4. If true use induction, else give the smallest value of n that it doe

ddd [48]

Answer:

The statement is true for every n between 0 and 77 and it is false for $n\geq 78$

Step-by-step explanation:

First, observe that, for n=0 and n=1 the statement is true:

For n=0: $\sum^{n}_{i=0} (2i)^4=0 \leq 0=(4n)^4$

For n=1: $\sum^{n}_{i=0} (2i)^4=16 \leq 256=(4n)^4$

From this point we will assume that $n\geq 2$

As we can see, $\sum^{n}_{i=0} (2i)^4=\sum^{n}_{i=0} 16i^4=16\sum^{n}_{i=0} i^4$ and $(4n)^4=256n^4$ . Then,

$\sum^{n}_{i=0} (2i)^4 \leq(4n)^4 \iff \sum^{n}_{i=0} i^4 \leq 16n^4$

Now, we will use the formula for the sum of the first 4th powers:

$\sum^{n}_{i=0} i^4=\frac{n^5}{5} +\frac{n^4}{2} +\frac{n^3}{3}-\frac{n}{30}=\frac{6n^5+15n^4+10n^3-n}{30}$

Therefore:

$\sum^{n}_{i=0} i^4 \leq 16n^4 \iff \frac{6n^5+15n^4+10n^3-n}{30} \leq 16n^4 \\\\ \iff 6n^5+10n^3-n \leq 465n^4 \iff 465n^4-6n^5-10n^3+n\geq 0$

and, because $n \geq 0$ ,

$465n^4-6n^5-10n^3+n\geq 0 \iff n(465n^3-6n^4-10n^2+1)\geq 0 \\\iff 465n^3-6n^4-10n^2+1\geq 0 \iff 465n^3-6n^4-10n^2\geq -1\\\iff n^2(465n-6n^2-10)\geq -1$

Observe that, because $n \geq 2$ and is an integer,

$n^2(465n-6n^2-10)\geq -1 \iff 465n-6n^2-10 \geq 0 \iff n(465-6n) \geq 10\\\iff 465-6n \geq 0 \iff n \leq \frac{465}{6}=\frac{155}{2}=77.5$

In concusion, the statement is true if and only if n is a non negative integer such that $n\leq 77$

So, 78 is the smallest value of n that does not satisfy the inequality.

Note: If you compute $(4n)^4- \sum^{n}_{i=0} (2i)^4$ for 77 and 78 you will obtain:

$(4n)^4- \sum^{n}_{i=0} (2i)^4=53810064$

$(4n)^4- \sum^{n}_{i=0} (2i)^4=-61754992$

7 0

3 years ago

Line AB passes through points A (-6,6) and B(12,3). If the equation of the line is written in slope-intercept form, y=mx+b, the.

Tomtit [17]

Answer:

You wrote the question wrong...

m is not -16 it is -1/6 (that is a big difference)

y=mx+b

y=-1/6x+b

3 = -1/6(12) + b

3 = -2 + b

b=5

Step-by-step explanation:

3 0

2 years ago

A temperature of 1.64◦F corresponds to Answer in units of ◦C.

Liula [17]

Answer:

(1,64 °F − 32) × 5/9 = 73,333 °C

7 0

3 years ago

What is 625 over 6561 simplified?

erastovalidia [21]

<span> the answer is 0.09526. your welcome</span>

4 0

3 years ago