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3 years ago

A rectangle has a perimeter of 64 inches and a length of 22 inches. Which equation can you solve to find the width?

2 answers:

6 0

It's B because if one length is 22 then both lengths combined is 44 + the width. Since there are 2 of those, each are represented with w so basically you're adding 2w to the total length,44 which will end up to look like 44+ 2w

Zielflug [23.3K]3 years ago

5 0

Perimeter is found by the formula 2l+2w, where l is the length and w is the width.

Since we have a length of 22 inches and a perimeter of 64 inches, the width can be found by solving the equation 2(22)+2w=64, or 2w+44=64.

:)

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Which expression can be used to find the surface area of the following triangular prism?

vichka [17]

(B) but if there is another answers let me see cuz all i see is a and b

7 0

3 years ago

Read 2 more answers

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

Evaluate 4a + 7b + 3a − 2b for a = 5 and b = −3.

blsea [12.9K]

Answer:

Step-by-step explanation:

$4a+7b+3a-2b\qquad\text{combine like terms}\\\\=(4a+3a)+(7b-2b)\\\\=7a+5b\qquad\text{put a = 5 and b = -3 to the expression}\\\\7(5)+5(-3)=35-15=20$

5 0

3 years ago

Jim drove 605 miles in 11 hours. At the same rate, how many miles would he drive in 13 hours?

svlad2 [7]

Answer: 715 Miles

Step-by-step explanation:

Divide 605 miles by 11 hours, which would give you how far he travels in 1 hour. (605/11=55) Since they give you 13 hours, multiply 13 hours by 55 miles which gets you 715 miles :)

8 0

3 years ago

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Annette [7]

$\implies {\blue {\boxed {\boxed {\purple {\sf {B)\:10}}}}}}$