Help! Please show work so I can fully understand.

Which value of b would make x²+bx-30 factorable? A. -31 B. -17 C. 11 D. 13

dimulka [17.4K]

Answer:

D. 13

Step-by-step explanation:

well since it's a quadratic equation, it can be written in the form of ax²+bx+c=0. So we have a=1, b=b and c= -30. Also the roots are given by the equation-

x= -b± $\sqrt{b^{2}-4ac}$ /2a. So all I did was put the number from the choices which would satisfy the sqrt part and that turned out to be 13 since $\sqrt{13^{2}-4*1*(-30)$ = $\sqrt{289}$ = 17. So b=13.

5 0

3 years ago

Read 2 more answers

Find the slope (-2,-4) (-5,5)

diamong [38]

Answer:

Your answer would be Slope m = -3

Step-by-step explanation:

Step 1: Graph the points on a coordinate plane( refer to image!)

Whenever your trying to find a slope of 2 order pairs, remember this

m = rise/run. ( Slope = rise over run.) = Δy/Δx

Now we solve:

M = rise/run = Δy/Δx

M = y2 - y1/x2-x1

M = 5 - (-4) / -5-(-2)

So we get M = 9/-3 and 9 divided by -3 is -3

So, the slope of (-2,-4) and (-5,5) is -3.

5 0

1 year ago

Help me now !!!!! help i need help

iren2701 [21]

cylinder:

V = πr²h

V = 3.14(2)² * 3

V = 3.14(4) * 3

V = 3.14(12)

V = 37.7m³

rectangular prism:

V = lwh

V = (2.4)(9)(5)

V = 108m³

the entirety of the sculpture:

V = volume of cylinder + volume of rectangular prism

V = 37.7 + 108

V = 145.7m³

4 0

1 year ago

An article written for a magazine claims that 78% of the magazine's subscribers report eating healthily the previous day. Suppos

Schach [20]

Answer:

89.44% probability that less than 80% of the sample would report eating healthily the previous day

Step-by-step explanation:

We use the binomial approximation to the normal to solve this question.

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

Can be approximated to a normal distribution, using the expected value and the standard deviation.

The expected value of the binomial distribution is:

$E(X) = np$

The standard deviation of the binomial distribution is:

$\sqrt{V(X)} = \sqrt{np(1-p)}$

Normal probability distribution

Problems of normally distributed samples 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.

When we are approximating a binomial distribution to a normal one, we have that $\mu = E(X)$ , $\sigma = \sqrt{V(X)}$ .