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2 years ago

Find the value of x and y using matrix method. 2x – 5y = 7 -2x + 4y = - 6

Mathematics

1 answer:

juin [17]2 years ago

6 0

9514 1404 393

Answer:

(x, y) = (1, -1)

Step-by-step explanation:

The augmented matrix of coefficients for these equations is ...

$\left[\begin{array}{cc|c}2&-5&7\\-2&4&-6\end{array}\right]$

The row-reduction function of your calculator can find the solution to the system of equations. The result of using that function is ...

$\left[\begin{array}{cc|c}1&0&1\\0&1&-1\end{array}\right]$

This tells you the solution is (x, y) = (1, -1).

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If f(x) = (5x^3 - 4)^4, then what is f '(x)?

vlabodo [156]

You apply the rule to put the exponent in front, and lower it by one. But since this is a nested expression, you apply it twice:

4*(5x^3-4)^3 * 3*5x^2 =

60x^2 (5x^3-4)^3

4 0

2 years ago

A particular telephone number is used to receive both voice calls and fax messages. Suppose that 25% of the incoming calls invol

bagirrra123 [75]

Answer:

a) 0.214 = 21.4% probability that at most 4 of the calls involve a fax message

b) 0.118 = 11.8% probability that exactly 4 of the calls involve a fax message

c) 0.904 = 90.4% probability that at least 4 of the calls involve a fax message

d) 0.786 = 78.6% probability that more than 4 of the calls involve a fax message

Step-by-step explanation:

For each call, there are only two possible outcomes. Either it involves a fax message, or it does not. The probability of a call involving a fax message is independent of other calls. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And p is the probability of X happening.

25% of the incoming calls involve fax messages

This means that $p = 0.25$

25 incoming calls.

This means that $n = 25$

a. What is the probability that at most 4 of the calls involve a fax message?

$P(X \leq 4) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4)$ .

In which

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 0) = C_{25,0}.(0.25)^{0}.(0.75)^{25} = 0.001$

$P(X = 1) = C_{25,1}.(0.25)^{1}.(0.75)^{24} = 0.006$

$P(X = 2) = C_{25,2}.(0.25)^{2}.(0.75)^{23} = 0.025$

$P(X = 3) = C_{25,3}.(0.25)^{3}.(0.75)^{22} = 0.064$

$P(X = 4) = C_{25,4}.(0.25)^{4}.(0.75)^{21} = 0.118$

$P(X \leq 4) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4) = 0.001 + 0.006 + 0.025 + 0.064 + 0.118 = 0.214$

0.214 = 21.4% probability that at most 4 of the calls involve a fax message

b. What is the probability that exactly 4 of the calls involve a fax message?

$P(X = 4) = C_{25,4}.(0.25)^{4}.(0.75)^{21} = 0.118$

0.118 = 11.8% probability that exactly 4 of the calls involve a fax message.

c. What is the probability that at least 4 of the calls involve a fax message?

Either less than 4 calls involve fax messages, or at least 4 do. The sum of the probabilities of these events is 1. So

$P(X < 4) + P(X \geq 4) = 1$

We want $P(X \geq 4)$ . Then

$P(X \geq 4) = 1 - P(X < 4)$

In which

$P(X < 4) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3)$

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 0) = C_{25,0}.(0.25)^{0}.(0.75)^{25} = 0.001$

$P(X = 1) = C_{25,1}.(0.25)^{1}.(0.75)^{24} = 0.006$

$P(X = 2) = C_{25,2}.(0.25)^{2}.(0.75)^{23} = 0.025$

$P(X = 3) = C_{25,3}.(0.25)^{3}.(0.75)^{22} = 0.064$

$P(X$

$P(X \geq 4) = 1 - P(X < 4) = 1 - 0.096 = 0.904$

0.904 = 90.4% probability that at least 4 of the calls involve a fax message.

d. What is the probability that more than 4 of the calls involve a fax message?

Very similar to c.

$P(X \leq 4) + P(X > 4) = 1$

From a), $P(X \leq 4) = 0.214)$

Then

$P(X > 4) = 1 - 0.214 = 0.786$

0.786 = 78.6% probability that more than 4 of the calls involve a fax message

8 0

2 years ago

Natalie sawed five boreds of equal length to make a stool. Each was 8 tenth of a meter long what is the total lenght of the boar

Dmitry [639]

One board is 31.5 inches long. all the boards together is 157.5 inches long

6 0

2 years ago

How tall is the tree? 5ft 35° -20ft- [? ]ft

SVEN [57.7K]

Answer:

$\boxed{\bf 19ft}$

Step-by-step explanation:

$\bf tan\:\theta =\cfrac{opp}{adj}$

$\bf tan(35^o)=\cfrac{x}{20}$

$\bf 20\;tan (35^o)=x$

$\bf 14ft=x$

The height of the tree:-

$\bf x+5ft$

$\bf 14ft+5ft$

$\bf 19ft$

3 0

1 year ago

Read 2 more answers

Suppose that you have just been hired at an annual salary of $85,000 and expect to receive an annual raise of 6% per year. What

Varvara68 [4.7K]

Answer:

$125,800

Step-by-step explanation:

Amount (A) = ?

Principal (P) = $85,000

Rate (r) = 6%

Time (t) = 8 years

Simple interest formula;

A = P(1 + rt)

A = $85,000(1 + 0.48)

A = $125,800

7 0

2 years ago