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3 years ago

Solve. x2 + 14 = 9x A) x = 2, x = 7 B) x = 3, x = 5 C) x = −2, x = −7 D) x = −3, x = −5

Mathematics

1 answer:

chubhunter [2.5K]3 years ago

7 0

Answer:

A) x = 2, x = 7

Step-by-step explanation:

x^2 + 14 = 9x

Subtract 9x from each side

x^2-9x + 14 = 9x-9x

x^2-9x + 14 = 0

What 2 numbers multiply to 14 and add to -9

-7*-2 = 14

-7+-2 = -9

(x-7)(x-2) = 0

Using the zero product property

x-7 = 0 x-2 =0

x=7 x=2

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Gina wants to make

gavmur [86]

Answer:

6.75 pounds

Step-by-step explanation:

This question is of direct variation. We will use x as our answer. 8 is 2/3 of 12, so 4.5 should be 2/3 of x. We can now make an equation.

$4.5=\frac{2}{3} x\\4.5*\frac{3}{2} =\frac{2}{3} x*\frac{3}{2} \\6.75=x$

In order to solve the equation, we multiply both sides by the reciprocal of 2/3, which is 3/2.

* stands for multiplication

From solving our equation, we get 6.75. We can't forget the units, so the answer is 6.75 pounds.

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3 years ago

The regression equation y=0.5x+1.3 approximates the number of hours it takes to arrange a dinner event, y, given the number of p

Sphinxa [80]

It would be C.

For example, say 1 person comes. This would be x=1. Plugging this in gives you,

y=0.5 + 1.3

This shows that C is true since x is always going to be multiplied by 0.5.

1.3 would be the base amount of time it takes to arrange since if it the y-intercept.

5 0

3 years ago

In answering a question on a multiple-choice test, a student either knows the correct answer or guesses it. Let 0.7 be the proba

Dahasolnce [82]

Answer:

The probability is 0.9211

Step-by-step explanation:

Let's call K the event that the student know the answer, G the event that the student guess the answer and C the event that the answer is correct.

So, the probability P(K/C) that a student knows the answer to a question, given that she answered it correctly is:

P(K/C)=P(K∩C)/P(C)

Where P(C) = P(K∩C) + P(G∩C)

Then, the probability P(K∩C) that the student know the answer and it is correct is:

P(K∩C) = 0.7

On the other hand, the probability P(G∩C) that the student guess the answer and it is correct is:

P(G∩C) = 0.3*0.2 = 0.06

Because, 0.3 is the probability that the student guess the answer and 0.2 is the probability that the answer is correct given that the student guess the answer.

Therefore, The probability P(C) that the answer is correct is:

P(C) = 0.7 + 0.06 = 0.76

Finally, P(K/C) is:

P(K/C) = 0.7/0.76 = 0.9211

7 0

3 years ago

Axis of sym: x =

marta [7]

Answer:

<h2>SEE BELOW</h2>

Step-by-step explanation:

<h3>to understand this</h3><h3>you need to know about:</h3>

quadratic function
PEMDAS

<h3>let's solve:</h3>

vertex:(h,k)

therefore

vertex:(-1,4)

axis of symmetry:x=h

therefore

axis of symmetry:x=-1

to find the quadratic equation we need to figure out the vertex form of quadratic equation and then simply it to standard form i.e ax²+bx+c=0

vertex form of quadratic equation:

y=a(x-h)²+k

therefore

y=a(x-(-1))²+4
y=a(x+1)²+4

it's to notice that we don't know what a is

therefore we have to figure it out

the graph crosses y-asix at (0,3) coordinates

so,

3=a(0+1)²+4

simplify parentheses:

$3 = a(1 {)}^{2} + 4$

simplify exponent:

$3 = a + 4$

therefore

$a = - 1$

our vertex form of quadratic equation is

y=-(x+1)²+4

let's simplify it to standard form

simplify square:

$y = - ( {x}^{2} + 2x + 1) + 4$

simplify parentheses:

$y = - {x}^{2} - 2x - 1 + 4$

simplify addition:

$y = - {x}^{2} - 2x + 3$

therefore our answer is D)y=-x²-2x+3

the domain of the function

$x\in \mathbb{R}$

and the range of the function is

$y\leqslant 4$

zeroes of the function:

$- {x}^{2} - 2x + 3 = 0$

$\sf divide \: both \: sides \: by \: - 1$

${x}^{2} + 2x - 3 = 0$

$\implies \: {x}^{2} + 3x - x + 3 = 0$

factor out x and -1 respectively:

$\sf \implies \: x(x + 3) - 1(x + 3 )= 0$

group:

$\implies \: (x - 1)(x + 3) = 0$

therefore

$\begin{cases} x_{1} = 1 \\ x_{2} = - 3\end{cases}$

4 0

3 years ago

204, 200,196,... find the 31st term

rewona [7]

Answer:

31st term = 84

Step-by-step explanation:

Given:

204, 200,196,...

Find:

31st term

Computation:

204, 200,196,...

First term a = 204

Difference d = a3 - a2

Difference d = 196 - 200

Difference d = -4

An = a + (n-1)d

A31 = 204 + (31-1)(-4)

A31 = 204 - 120

A31 = 84

6 0

3 years ago

Read 2 more answers