Pls help meh i will give brainlyest

I really need help with this

zysi [14]

Answer:

Our system of equations is:

y+2x+1=0
4y-4x²-12x = -7

We are looking for x

Let's express y using x

y+2x+1=0
y= -2x-1

Replace x in the second equation with the result

4y-4x²-12x = -7
4(-2x-1)-4x²-12x = -7
-8x-4-4x²-12x = -7
-8x-4x²-12x = -7+4
-4x²-20x = -3
-4x²-20x+3 = 0 multiply by -1 to get rid of the - signs with x
4x²+20x-3=0

4x²+20x+3=0 is a quadratic equation

Let Δ be our discriminant

a= 4
b= 20
c= -3

Δ= 20²-4*4*(-3)

Δ=448 > 0 so we have two solutions for x

let x and x' be the solutions

x = $\frac{-20-\sqrt{448} }{8}$ = -5.145 ≈ -5.15
x'= $\frac{-20+\sqrt{448} }{8}$ = 0.145≈ 0.15

so the solutions are:

-5.15 and 0.15

7 0

3 years ago

Simplify the following expression.

aliina [53]

The answer to the question

6 0

3 years ago

One water quality standard for water that is discharged into a particular type of stream or pond is that the average daily water

musickatia [10]

Answer:

$t=\frac{18.15-18}{\frac{3.134}{\sqrt{6}}}=0.117$

$p_v =P(t_{5}>0.117)=0.456$

If we compare the p value and the significance level given $\alpha=0.1$ we see that $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can conclude that the mean is not significantly higher than 18 at 10% of signficance.

Step-by-step explanation:

Data given and notation

16.8 21.5 19.1 12.8 18.0 20.7

We can calculate the mean and deviation with the following formulas:

$\bar X = \frac{\sum_{i=1}^n X_i}{n}$

$s= \sqrt{\frac{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}}$

And the results are:

$\bar X=18.15$ represent the sample mean

$s=3.134$ represent the sample standard deviation

$n=6$ sample size

$\mu_o =18$ represent the value that we want to test

$\alpha=0.1$ represent the significance level for the hypothesis test.

z would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the true mean is higher than 18, the system of hypothesis would be:

Null hypothesis: $\mu \leq 18$

Alternative hypothesis: $\mu > 18$

Since we don't know the population deviation, is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}$ (1)

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$t=\frac{18.15-18}{\frac{3.134}{\sqrt{6}}}=0.117$

P-value

The degrees of freedom are given by:

$df = n-1 = 6-1= 5$

Since is a right tailed test the p value would be:

$p_v =P(t_{5}>0.117)=0.456$

Conclusion

If we compare the p value and the significance level given $\alpha=0.1$ we see that $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can conclude that the mean is not significantly higher than 18 at 10% of signficance.

3 0

3 years ago

I NEED HELP PLZZZ *WILL MARK BRAINLIEST WHEN I CAN* Find the percent of decrease from 15 touchdowns to 6 touchdowns.

Ipatiy [6.2K]

Answer:

60% decrease.

Step-by-step explanation:

Let's use a ratio:

touchdowns : decreased

15 : 6

5 : 2

100 : 40

The percent decrease is 60%

7 0

3 years ago

"X is the number of red marbles that Tonya has in her hand after she selects four marbles from a bag containing four red marbles

Paladinen [302]

Answer:

Explained below.

Step-by-step explanation:

There are four red marbles (R) and two green marbles (G) in the bag.

The random variable X is defined as the number of red marbles that Tonya has in her hand after she selects four marbles from the bag.

The probability of selecting a red marble is:

$P(X)=\frac{4}{6}=0.667$

The sample space of X can be defined as follows:

Outcomes: {(RGGG), (RRGG), (RRRG), (RRRR), (RRGR), (RGRR), (GRRR), (RGRG), (GRRG), (RGGR), (GRGR), (GRGG), (GGRG), (GGGR), (GGGG)}

So, the sample space of X is:

S = {0, 1, 2, 3 and 4}

7 0

3 years ago