Hey can someone pls help me asap?!

Rationalise the denominator by 6 root 7 minus 1

nikklg [1K]

Answer:

Assuming the numerator was 1.

$(6\sqrt{7}+1)/251$

Step-by-step explanation:

Assuming the numerator was 1.

$1/(6\sqrt{7} -1)\\ (6\sqrt{7}+1)/((6\sqrt{7} - 1)(6\sqrt{7} + 1))\\ (6\sqrt{7}+1)/((6\sqrt{7})^2 + 6\sqrt{7} - 7\sqrt{7} - 1)\\(6\sqrt{7}+1)/((6\sqrt{7})^2 - 1)\\(6\sqrt{7}+1)/((36*7 - 1)\\(6\sqrt{7}+1)/251$

7 0

2 years ago

(5a^2+6a+2)-(7a^2-7a-5)

krok68 [10]

For this case we must simplify the following expression: $(5a^ 2 + 6a + 2) - (7a^ 2-7a-5) =$

We eliminate the parentheses taking into account that:

$- * + = -\\- * - = +$

So:

$5a ^ 2 + 6a + 2-7a ^ 2 + 7a + 5 =$

We add similar terms taking into account that:

Equal signs are added and the same sign is placed.

Different signs are subtracted and the major sign is placed.

$5a ^ 2-7a^2 + 6a + 7a +2 +5 =\\-2a ^ 2 + 13a + 7$

Answer:

$-2a ^ 2 + 13a + 7$

8 0

3 years ago

A packing box is a rectangular prism with volume 2 m3.

Firlakuza [10]

Answer:

The hight of the box is 1.2 m

Step-by-step explanation:

250cm= 2.5m

100cm= 1m

2.5x1=2.5

3/2.5=1.2

2.5 x 1 x 1.2= $3m^{3}$

6 0

2 years ago

A set of test scores is normally distributed with a mean of 130 and a standard deviation of 30 What score is necessary to reach

nlexa [21]

Answer:

A score of 150.25 is necessary to reach the 75th percentile.

Step-by-step explanation:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

A set of test scores is normally distributed with a mean of 130 and a standard deviation of 30.

This means that $\mu = 130, \sigma = 30$

What score is necessary to reach the 75th percentile?

This is X when Z has a pvalue of 0.75, so X when Z = 0.675.

$Z = \frac{X - \mu}{\sigma}$

$0.675 = \frac{X - 130}{30}$

$X - 130 = 0.675*30$

$X = 150.25$

A score of 150.25 is necessary to reach the 75th percentile.

7 0

3 years ago

A manufacturer is planning to sell a new product at the price of 210 dollars per unit and estimates that if x thousand dollars i

sattari [20]

Answer:

Development costs: $2757

Promotion costs: $3155

Step-by-step explanation:

This might seem like a two-variable problem, but in actuality it's not - because the demand function is a sum of two components, each being independent and using only one variable, we can solve for the two separately.

Moreover, the price per unit and cost per unit is constant, so each product yields exactly $80 ($210 - $130).

Let's solve separately.

We need to maximize:

$80 * 160y/(y+4) - 1000y = $12800 * y/(y+4) - $1000*y

$80 * 170x/(x+7) - 1000x = $13600 * x/(x+7) - $1000*x

Let's go:

$12800 * y/(y+4) - $1000*y = $12800 * (1 - 4/(y+4)) - $1000y = $12800 - $51200/(y+4) - $1000*y

we analyze the derivative. $12800 is a constant, so we can skip it. Derivative of 1/(y+4) is -(y+4)^-2, derivative of $1000y is $1000.

deriv = $51200/(y+4)/(y+4) - $1000

We find the changepoints by analyzing $51200/(y+4)/(y+4) - $1000 = $0. We don't need to worry about y+4 = 0 because we cannot spend negative money on development/advertisement.

(y+4)^2 = $51.2

y+4 ~= 7.155417528 (or -y-4 = 7.1554... but it doesn't make sense because negative budget so we don't analyze).

y ~= 3.155417528

lastly, we should check that it's actually a maximum there - but it is, the original function goes to negative infinity.

rounding $1000y to the nearest dollar gives us $3155

Let's do the same for x:

$13600 * x/(x+7) - $1000*x = $13600 * (1 - 7/(x+7)) - $1000x = $13600 - $95200/(x+7) - $1000*x

deriv = $95200/(x+7)/(x+7) - $1000

$95200/(x+7)/(x+7) - $1000 = $0

(x+7)^2 = 95.2

(x+7) ~= 9.75704873412

x ~= 2.75704...

rounding $1000x to the nearest dollar yields $2757

3 0

2 years ago