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3 years ago

Use the quadratic formula to solve x2 – 3x - 2 = 0.

Mathematics

2 answers:

BlackZzzverrR [31]3 years ago

8 0

Answer:

2.5 or 3.5

Step-by-step explanation:

The quadratic formula is $x = -b +/- \frac{\sqrt{b^2 + 4ac}}{2a}$ .

a, b, and c are determined by the terms in the formula ax^2 + bx + c

They gave you the equation x^2 - 3x - 2, which fits that formula. a is 1, b is -3, and c is -2. So plug those values into the equation:

$x = -(-3) +/- \frac{\sqrt{(-3)^2 + 4(1)(-2)}}{2(1)}$

$x = 3 +/- \frac{\sqrt{9 -8}}{2}$

$x = 3 +/- \frac{\sqrt{1}}{2}$

$x = 3 +/- \frac{1}{2}$

So x is 3 plus or minus -1/2. 3 plus -1/2 is 2.5

3 minus -1/2 is 3.5

So the 2 possible x values are 2.5 and 3.5.

r-ruslan [8.4K]3 years ago

6 0

Answer:

x = 2 , 1

Step-by-step explanation:

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An urn contains 3 red and 7 black balls. Players A and B take turns (A goes first) withdrawing balls from the urn consecutively.

andrey2020 [161]

Answer:

The probability that A selects the first red ball is 0.5833.

Step-by-step explanation:

Given : An urn contains 3 red and 7 black balls. Players A and B take turns (A goes first) withdrawing balls from the urn consecutively.

To find : What is the probability that A selects the first red ball?

Solution :

A wins if the first red ball is drawn 1st,3rd,5th or 7th.

A red ball drawn first, there are $E(1)= ^9C_2$ places in which the other 2 red balls can be placed.

A red ball drawn third, there are $E(3)= ^7C_2$ places in which the other 2 red balls can be placed.

A red ball drawn fifth, there are $E(5)= ^5C_2$ places in which the other 2 red balls can be placed.

A red ball drawn seventh, there are $E(7)= ^3C_2$ places in which the other 2 red balls can be placed.

The total number of total event is $S= ^{10}C_3$

The probability that A selects the first red ball is

$P(A \text{wins})=\frac{(^9C_2)+(^7C_2)+(^5C_2)+(^3C_2)}{^{10}C_3}$

$P(A \text{wins})=\frac{36+21+10+3}{120}$

$P(A \text{wins})=\frac{70}{120}$

$P(A \text{wins})=0.5833$

6 0

3 years ago

A number divided by 35 has a quotient of 8 with a remainder of 9? What is the number?

marissa [1.9K]

Answer: 311.5

Step-by-step explanation: 35*8.9=311.5

311.5/35=8.9

7 0

3 years ago

Read 2 more answers

If angle a measures 64 then what does angle b measure?

Naddik [55]

Answer:

b = 26°

Step-by-step explanation:

a ; b = complementary =>

a + b = 90° } => b = 90° - 64° = 26°

a = 64°

8 0

3 years ago

Read 2 more answers

PLZ HELP! A train averages a speed of 90 miles per hour across the plains and 37.5 miles per hour through the mountains. If a tr

Kruka [31]

Answer:

3.8

Step-by-step explanation:

A train averages a speed of 90 miles per hour across the plains and 37.5 miles per hour through the mountains.

If a trip of 300 miles took 3 hour and 48 minutes, how much of it was through the mountains?

Let d = distance traveled at 37.5 (thru the mountains)

then

(300-d) = distance traveled at 90 mph

Write a time equation, time = dist/speed

change 3 hr 48 min to hrs: 3 + 48/60 = 3.8 hrs

plain time + mountain time = 3.8 hrs

%28300-d%29%2F90 + d%2F37.5 = 3.8

Multiply 90*37.5

3375*%28300-d%29%2F90 + 3375*d%2F37.5 = 3.8(3375)

cancel the denominator

37.5(300-d) + 90d = 12825

11250 - 37.5d + 90d = 12825

52.5d = 1575

d = 1575/52.5

d = 30 mi thru the mountains

Check this, find the distance on the plain

300-30 = 270 mi

Find the actual time at each speed

270/90 = 3 hrs

30/37.5 = .8 hrs

-----------------

total time: 3.8 hrs

7 0

3 years ago

The Johnson twins were born five years after their older sister. This year, the product of the three siblings' ages is exactly

Mamont248 [21]

Answer:

13 years.

Step-by-step explanation:

Suppose, today, the Johnson twins' age is x years. Then the age of their elder sister will be (x + 5) years old. It is given that product of the three siblings' ages is exactly 2998 more than the sum of their ages. Therefore:

x + x + x + 5 + 2998 = (x)(x)(x + 5).

3x + 3003 = x^3 + 5x^2.

x^3 + 5x^2 - 3x - 3003 = 0.

To solve the question, factor theorem will be used. It states if any number c satisfies the equation f(c) = 0, then c is the factor of f(x). By observation, it can be seen that x = 13 can be a possible candidate for the factor of f(x). To verify, check f(13).

f(13) = 13^3 + 5(13^2) - 3(13) - 3003 = 2197 + 845 - 39 - 3003 = 0.

Since f(13) = 0, therefore x = 13 is the factor of f(x).

Now applying synthetic division:

Column 1 2 3 4 5

13 | 1 5 -3 -3003 (Row 1)

______|______<u> _13__234___3003</u> (Row 2)

| 1 18 231 0 (Row 3)

The method requires to write the coefficients of all the powers in the Row 1 on the right hand side of the table. Put the factor x = 13 on the left hand side of the table (Row 1 Column 1). The first step involves the second column elements to be added. Since there is only 1, thus there will be 1 below the line. Next step involves multiplying 1 with the factor (which is 13) and this will be the element for row 2 column 3. The add the elements of the column 3. The answer comes out to be -3. Repeat the above steps for the columns 4 and 5. The sum of the column 5 (the last column) should be 0, which is the case. The elements of the last row are actually the coefficients of the quadratic equation which is resultant from dividing f(x) by (x - 13). Thus:

x^2 + 18x + 231 = 0.

Using completing the square:

x^2 + 18 = -231.

(x)^2 + 2*(x)*(9) + (9)^2 = -231 + (9)^2.

(x + 9)^2 = -231 + 81.

(x + 9)^2 = -150.

Taking square root on both sides shows that rest of the 2 answers of this polynomial will be complex roots since square root of -150 does not exist in real numbers. Therefore, since the age is a real quantity and not a complex quantity, the age of the twins is 13 years!!!

8 0

3 years ago