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3 years ago

What is the height of a triangle with area 40 square inches and base 20 inches? A. 2 in. B. 1 in. C. 4 in. D. 3 in.

Mathematics

2 answers:

maxonik [38]3 years ago

5 0

Answer:

Step-by-step explanation:

base×height÷2=area of a triangle

20×height÷2=40

40×2÷20=4

UNO [17]3 years ago

4 0

The answer is A. Hope this helps.

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What is the factor tree of 8

8090 [49]

THE FACTOR TREE IS : 8=2^3

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3 years ago

Please show me how to solve the problem

AlladinOne [14]

Answer:

(3x+1)

Step-by-step explanation:

So i start by the little 2 and then the 3 and then 19x +6

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2 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

Please help with problem !!!

True [87]

Answer:

Step-by-step explanation:

y = 2x^2 - 12x +19 Put brackets around the 1st 2 terms. Take 2

y = 2(x^2 - 6x ) + 19 Take 1/2 of the 6 square it and add inside the brackets

y = 2(x^2 - 6 + (6/2)^2) +19 Subtract 2 *9 from the 19. Express 1st 3 terms as ( )^2

y = 2(x- 3)^2 + 19 - 18

y = 2(x - 3)^2 + 1

Answers

y intercept when x = 0 is y = 19

axis of symmetry x = 3

vertex: (3,1)

Graph

graph: red

axis of symmetry: blue

y intercept, vertex: green

7 0

3 years ago

A scientist measured the exact distance between two points on a map and came up with the following number: 0.04000 km.

stellarik [79]

Answer:

The first zero after decimal point and 4 only

Step-by-step explanation:

Despite having 5 decimal points, the rules of significant figures dictate that unless there is a digit other than zero after, the only significant numbers are those that come before zero. For this case, the significant digits are only 0.04 but if it was 0.0400005 then all the other zeros would have also be considered significant.

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3 years ago