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Nitella [24]
3 years ago
8

Solve the system using substitution 8x+9y=15 5x-2y=17

Mathematics
1 answer:
Otrada [13]3 years ago
8 0

5x-2y=17\ \ \ \ |-5x\\-2y=-5x+17\ \ \ \ |:(-2)\\y=2.5x-8.5\\\\\text{substitute to the first equation}\\\\9x+9(2.5x-8.5)=17\ \ \ \ |\text{use distributive property}\\9x+22.5x-76.5=17\ \ \ \ |+76.5\\31.5x=93.5\ \ \ \ |:31,5\\x=3\\\\\text{substitute the value of x to the equation}\ y=2.5x-8.5\\\\y=2.5(3)-8.5=7.5-8.5=-1\\\\Answer:\ x=3,\ y=-1\to(3;\ -1)

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Solve Quadratic Equations by Factoring:
mr_godi [17]

Answer:

  1. x = 0 or 1
  2. x = ±i/4
  3. x = -5 (twice)

Step-by-step explanation:

Factoring is aided by having the equations in standard form. The first step in each case is to put the equations in that form. The zero product property tells you that a product is zero when a factor is zero. The solutions are the values of x that make the factors zero.

1. x^2 -x = 0

  x(x -1) = 0 . . . . . x = 0 or 1

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2. 16x^2 +1 = 0

This is the "difference of squares" ...

  (4x)^2 - (i)^2 = 0

  (4x -i)(4x +i) = 0 . . . . . x = -i/4 or i/4 (zeros are complex)

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3. x^2 +10x +25 = 0

  (x +5)(x +5) = 0 . . . . . x = -5 with multiplicity 2

5 0
3 years ago
Lisa is mailing a letter to a friend. Postage costs $0.32 for the first ounce and $0.23 for the additional ounce. How heavy can
Advocard [28]

Answer: 8.3 ounces

Step-by-step explanation:

simple, there's a flat fee for 1 ounce, then 23 cents for each ounce following.

so $2 - $0.32 = $1.68

1.67 / 0.23 = 7.3 ounces

7.3 ounces + 1 ounces (from the flat fee we subtracted)

which equals 8.3

7 0
2 years ago
42 is 21% of what number
Gnom [1K]
\begin{array}{ccc}42&-&21\%\\x&-&100\%\end{array}\ \ \ \ \ |cross\ multiply\\\\21x=42\times100\\\\21x=4200\ \ \ \ \ |divide\ both\ sides\ by\ 21\\\\\boxed{x=200}\leftarrow answer
5 0
3 years ago
Read 2 more answers
Two integers will be randomly selected from the sets above, one integer from set A and one integer from set B. What is the proba
Fittoniya [83]

Question:

A = {2, 3, 4, 5}

B = {4, 5, 6, 7, 8}

Two integers will be randomly selected from the sets above, one integer from set A and one integer from set B. What is the probability that the sum of the two integers will equal 9?

A. 0.15

B. 0.20

C. 0.25

D. 0.30

E. 0.33

Answer:

Option B: 0.20 is the probability of the sum of the two integers.

Explanation:

The sample space for selecting 2 numbers is given by

4\times 5 = 20

We need to determine the probability that the sum of two integers will be equal to 9.

Hence, we need to add the two integers from the sets A and B such that their sum will be equal to 9.

Hence, the sets are (2,7),(3,6),(4,5),(5,4)

Thus, the total number of sets whose sum is equal to 9 = 4

The probability that the sum of the two integers will equal 9 is given by

P=\frac{4}{20}

P=\frac{1}{5}

P=0.20

Thus, the probability that the sum of the two integers will equal 9 is 0.20

Hence, Option B is the correct answer.

4 0
3 years ago
I need some help please
dimulka [17.4K]
I think the answer is the third one, but idk.
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3 years ago
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