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3 years ago

What are the exact solutions of x2 − 3x − 1 = 0?

2 answers:

7 0

Hi, the quadratic formula is: $\boxed{X= \dfrac{-b \pm \sqrt{b ^{2}-4ac } }{2a}}$

Values: a = 1; b = - 3; c = -1
Solving:

$X ^{2}-3X-1=0$

$X= \dfrac{-(-3) \pm \sqrt{(-3) ^{2}-4(1)(-1) } }{2(1)}$

$X= \dfrac{3 \pm \sqrt{9+4} }{2}$

$X= \dfrac{3 \pm \sqrt{13} }{2}\ ===\ \textgreater \ \ Answer:\ \boxed{ \textbf{Option\ {C.}}}$

GOOD LUCK...!!!

kobusy [5.1K]3 years ago

3 0

Option C is the answer!

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F(x) = 9x-7. If f(x)= -7, find x.

svlad2 [7]

Answer: the answer is 56

Step-by-step explanation: since the f(x) is -7 it would be 9 times -7 then minus 7 and get the answer.

3 0

3 years ago

A new test to detect TB has been designed. It is estimated that 88% of people taking this test have the disease. The test detect

Elodia [21]

Answer:

Correct option: (a) 0.1452

Step-by-step explanation:

The new test designed for detecting TB is being analysed.

Denote the events as follows:

<em>D</em> = a person has the disease

<em>X</em> = the test is positive.

The information provided is:

$P(D)=0.88\\P(X|D)=0.97\\P(X^{c}|D^{c})=0.99$

Compute the probability that a person does not have the disease as follows:

$P(D^{c})=1-P(D)=1-0.88=0.12$

The probability of a person not having the disease is 0.12.

Compute the probability that a randomly selected person is tested negative but does have the disease as follows:

$P(X^{c}\cap D)=P(X^{c}|D)P(D)\\=[1-P(X|D)]\times P(D)\\=[1-0.97]\times 0.88\\=0.03\times 0.88\\=0.0264$

Compute the probability that a randomly selected person is tested negative but does not have the disease as follows:

$P(X^{c}\cap D^{c})=P(X^{c}|D^{c})P(D^{c})\\=[1-P(X|D)]\times{1- P(D)]\\=0.99\times 0.12\\=0.1188$

Compute the probability that a randomly selected person is tested negative as follows:

$P(X^{c})=P(X^{c}\cap D)+P(X^{c}\cap D^{c})$

$=0.0264+0.1188\\=0.1452$

Thus, the probability of the test indicating that the person does not have the disease is 0.1452.

4 0

3 years ago

there are 2 ones, 1 five,3tens, and 1 twenty. if there are 28 bills in her wallet, what would you predict is the approximate val

Kruka [31]

There would be 8 ones, 4 fives, 12 tens, and 4 twenties. That together would be about $228

4 0

4 years ago

what is the point-slope form of the equation of the line passing through the points (–6, –4) and (2, –5).

ioda

Answer:

The equation of the line would be y + 4 = -1/8(x + 6)

Step-by-step explanation:

To find the point-slope form of the line, start by finding the slope. You can do this using the slope formula below along with the two points.

m(slope) = (y2 - y1)/(x2 - x1)

m = (-4 - -5)/(-6 - 2)

m = 1/-8

m = -1/8

Now that we have the slope, we can use that along with one of the points in the base form of point-slope.

y - y1 = m(x - x1)

y + 4 = -1/8(x + 6)

7 0

3 years ago

Could someone pls help me with this question!!!

romanna [79]

Answer:

15 weeks

Step-by-step explanation:

Jon will increase his weigh 2 lbs a week which means he will be 178 lbs in 15 weeks{148+(15*2)} while Matt will decrease his weight from 1 lbs which means he will be 178 lbs in 15 weeks (193-15=178).

3 0

3 years ago