4 + 5x = 3 (-x + 3) -11

You want to buy three books that are on sale at 20% off. The original prices of the books are $2.50, $4.95, and $6.00. How much

Anon25 [30]

First add the prices of the original books.

2.5+4.95+6=11.45

Find 20% of 11.45

=2.29

Therefore I saved $2.29

8 0

3 years ago

The roots of a quadratic equation ax2+bx+c=0 are 3+sqrt2 and 3−sqrt2. Find the values of b and c assuming that a=1.

slamgirl [31]

Answer:

$b=-6\\c=7$

Step-by-step explanation:

we know that

The general equation of a quadratic function in factored form is equal to

$y=a(x-x_1)(x-x_2)$

where

a is a coefficient of the leading term

x_1 and x_2 are the roots

we have

$a=1\\x_1=3+\sqrt{2}\\x_2=3-\sqrt{2}$

substitute

$y=(1)(x-(3+\sqrt{2}))(x-(3-\sqrt{2}))$

Applying the distributive property convert to expanded form

$y=x^2-x(3-\sqrt{2})-x(3+\sqrt{2})+(3+\sqrt{2})(3-\sqrt{2})$

$y=x^2-(3x-x\sqrt{2})-(3x+x\sqrt{2})+(9-2)$

$y=x^2-3x+x\sqrt{2}-3x-x\sqrt{2}+7$

$y=x^2-6x+7$

therefore

$b=-6\\c=7$

7 0

2 years ago

Tell me please we are timed hurry

padilas [110]

Answer: 255

Step-by-step explanation:

7 0

2 years ago

Read 2 more answers

Someone please help me with this question

Sauron [17]

Answer:

3

Step-by-step explanation:

Again, anything to the 0th power is equal to 1.

The 0th power is attached to the b, so this means that b = 1. Multiply 9 and (1) together to get 9.

Now you can subtract 9 from 12 to get 3 as your final answer.

5 0

2 years ago

Read 2 more answers

a survey amony freshman at a certain university revealed that the number of hours spent studying the week before final exams was

Marat540 [252]

Answer:

Probability that the average time spent studying for the sample was between 29 and 30 hours studying is 0.0321.

Step-by-step explanation:

We are given that the number of hours spent studying the week before final exams was normally distributed with mean 25 and standard deviation 15.

A sample of 36 students was selected.

Let $\bar X$ = sample average time spent studying

The z-score probability distribution for sample mean is given by;

Z = $\frac{ \bar X-\mu}{\frac{\sigma}{\sqrt{n} } }} }$ ~ N(0,1)

where, $\mu$ = population mean hours spent studying = 25 hours

$\sigma$ = standard deviation = 15 hours

n = sample of students = 36

The Z-score measures how many standard deviations the measure is away from the mean. After finding the Z-score, we look at the z-score table and find the p-value (area) 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.

Now, Probability that the average time spent studying for the sample was between 29 and 30 hours studying is given by = P(29 hours < $\bar X$ < 30 hours)

P(29 hours < $\bar X$ < 30 hours) = P( $\bar X$ < 30 hours) - P( $\bar X$ $\leq$ 29 hours)

P( $\bar X$ < 30 hours) = P( $\frac{ \bar X-\mu}{\frac{\sigma}{\sqrt{n} } }} }$ < $\frac{ 30-25}{\frac{15}{\sqrt{36} } }} }$ ) = P(Z < 2) = 0.97725

P( $\bar X$ $\leq$ 29 hours) = P( $\frac{ \bar X-\mu}{\frac{\sigma}{\sqrt{n} } }} }$ $\leq$ $\frac{ 29-25}{\frac{15}{\sqrt{36} } }} }$ ) = P(Z $\leq$ 1.60) = 0.94520

So, in the z table the P(Z $\leq$ x) or P(Z < x) is given. So, the above probability is calculated by looking at the value of x = 2 and x = 1.60 in the z table which has an area of 0.97725 and 0.94520 respectively.

Therefore, P(29 hours < $\bar X$ < 30 hours) = 0.97725 - 0.94520 = 0.0321

Hence, the probability that the average time spent studying for the sample was between 29 and 30 hours studying is 0.0321.

7 0

2 years ago