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3 years ago

What is the value of x in the equation 3x-4y=65, when y=4?

Mathematics

2 answers:

irina [24]3 years ago

7 0

Answer:

Step-by-step explanation:

-4 x 4=-16 so you add the 16 to the 65 and get 81 so then you divide the 3 from the x so it would be 81/3=27

Softa [21]3 years ago

5 0

Answer:

$\boxed{ \bold{ \huge{ \boxed { \sf{x = 27}}}}}$

Step-by-step explanation:

Given, value of y = 4

To find : Value of x

$\sf{3x - 4y = 65}$

plug the value of y

$\dashrightarrow{ \sf{3x - 4 \times 4 = 65}}$

Multiply the numbers : 4 and 4

$\dashrightarrow{ \sf{3x - 16 = 65}}$

Move 16 to right hand side and change it's sign

$\dashrightarrow{ \sf{3x = 65 + 16}}$

Add the numbers : 65 and 16

$\dashrightarrow{ \sf{3x = 81}}$

Divide both sides by 3

$\dashrightarrow{ \sf{ \frac{3x}{3} = \frac{81}{3} }}$

Calculate

$\dashrightarrow{ \sf{ x = 27}}$

Hope I helped!

Best regards! :D

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8x -y=2. 5x-4y=3 please help solve this system by substition method

Vitek1552 [10]

8x-y=2 ---> y=8x-2
5x-4y=3

5x-4(8x-2)=3
5x-32x+8=3
-27x+8=3
-27x=-5
x= 5/27

8(5/27)-y=2
40/27-y=2
y=-14/27

6 0

3 years ago

For what value of X is the rational expression below equal to zero

stealth61 [152]

Answer:

Step-by-step explanation:

Step-by-step explanation:

if you divide 0 by any number you will get 0!!!

if you will substitute x for 2 you will have:

2-2/2+2 = 0/4 = 0

3 0

3 years ago

Question number 7 Give a reasonable domain and range for the function in this context

alina1380 [7]

Answer: D: [0, ∞)

R: [0, ∞)

Step-by-step explanation:

f(x) = 1.5x

x is the number of bottles

f(x) is the cost

Domain is the x-values. The least amount of bottles you can buy is 0 and the most you can buy is infinite <em>(technically you can only buy the amount you can afford and the amount the store has to sell but for mathematical purposes you can buy an infinite amount)</em>

So, the domain (D) is x = 0 to ∞ → D: [0, ∞)

Range is the y-values. The least and most amounts are based on the domain. Since the smallest x-value is 0, input that value into the equation to solve for f(x). Similarly, input the greatest x-value to solve for f(x).

f(x) = 1.5(0)

= 0

f(x) = 1.5(∞)

= ∞

So, the range (R) is f(x) = 0 to ∞ → R: [0, ∞)

3 0

4 years ago

105. Suppose that the probability that an adult in America will watch the Super Bowl is 40%. Each person is considered independe

Ainat [17]

Answer:

a. X is the number of adults in America that need to be surveyed until finding the first one that will watch the Super Bowl.

b. X can take any integer that is greater than or equal to 1. $\rm X\in \mathbb{Z}^{+}$ .

c. $\rm X \sim NB(1, 0.40)$ .

d. $E(\rm X) = 2.5$ .

e. $P(\rm X = 7) = 0.0187$ .

f. $P(\text{X} = 3) +P(\text{X} = 4) = 0.230$ .

Step-by-step explanation:

In this setting, finding an adult in America that will watch the Super Bowl is a success. The question assumes that the chance of success is constant for each trial. The question is interested in the number of trials before the first success. Let X be the number of adults in America that needs to be surveyed until finding the first one who will watch the Super Bowl.

It takes at least one trial to find the first success. However, there's rare opportunity that it might take infinitely many trials. Thus, X may take any integer value that is greater than or equal to one. In other words, X can be any positive integer: $\rm X\in \mathbb{Z}^{+}$ .

There are two discrete distributions that may model X:

The geometric distribution. A geometric random variable measures the number of trials before the first success. This distribution takes only one parameter: the chance of success on each trial.
The negative binomial distribution. A negative binomial random variable measures the number of trials before the r-th success. This distribution takes two parameters: the number of successes $r$ and the chance of success on each trial $p$ .

$\rm NB(1, p)$ (note that $r=1$ ) is equivalent to $\sim Geo(p)$ . However, in this question the distribution of $\rm X$ takes two parameters, which implies that $\rm X$ shall follow the negative binomial distribution rather than the geometric distribution. The probability of success on each trial is $40\% = 0.40$ .

$\rm X\sim NB(1, 0.40)$ .

The expected value of a negative binomial random variable is equal to the number of required successes over the chance of success on each trial. In other words,

$\displaystyle E(\text{X}) = \frac{r}{p} = \frac{1}{0.40} = 2.5$ .

$P(\rm X = 7) = 0.0187$ .

Some calculators do not come with support for the negative binomial distribution. There's a walkaround for that as long as the calculator supports the binomial distribution. The r-th success occurs on the n-th trial translates to (r-1) successes on the first (n-1) trials, plus another success on the n-th trial. Find the chance of (r-1) successes in the first (n-1) trials and multiply that with the chance of success on the n-th trial.

$P(\text{X} = 3)+P(\text{X} = 4) = 0.230$ .

3 0

3 years ago

Joni’s hair is 13 inches long and grows at an average rate of ⅔ in per month. Her friend Kate’s hair is 16 inches long and grows

ale4655 [162]

Answer:

Step-by-step explanation:

13 + (⅔)t = 16 + (½)t

(⅔ - ½)t = 3

t/6 = 3

t = 18

6 0

4 years ago