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Reptile [31]
3 years ago
6

X^2 - 2x = 15 how do I solve this quadratic method?I am stuck on it.... please help​

Mathematics
2 answers:
Anarel [89]3 years ago
6 0

Answer:

(x - 5)(x + 3)

Step-by-step explanation:

to solve x² - 2x = 15, we need to get all the terms on one side so we can solve the quadratic equation using factoring. to do this, we subtract 15 from both sides

x² - 2x = 15

- 15         -15

x² - 2x - 15 = 0

now we can factor. we need 2 numbers that when multiplied together give us -15, and when those 2 numbers are added together we get -2

because we have a -15, we can assume that one number must be negative and the other positive, as a negative times a postive is a negative.

we can use 3 and -5 as factors and test it out. we put x in front because we have an x²

(x - 5)(x + 3) < we can FOIL to check to see if this is correct. its not mandatory to check but when you arent sure of the answer you can FOIL it out

FOIL stands for: First, Outside, Inside, and Last terms

F: (x - 5)(x + 3) = x²

O: (x - 5)(x + 3) = -3x

I: (x - 5)(x + 3) = 5x

L: (x - 5)(x + 3) = -15

x² + 3x - 5x - 15 < subtract 3x from 5x

x² - 2x - 15

this checks out, so our answer is (x - 5)(x + 3)

mixas84 [53]3 years ago
4 0

Answer:

x=5, x=-3

Step-by-step explanation:

x^2-2x=15\\x^2-2x-15=0\\

next factor

 look at 1st image attached

-5 and 3 multiply to be -15 and add to be -2

so (x-5) (x+3)

to get what x equals set each part equal to 0 by flipping the signs

x=5 x=-3

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(a/5) - (b/3) = (a/2) - (b/6), solve for a
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Answer:

a =  -  \frac{10}{17} b

Step-by-step explanation:

(a/5) - (b/3) = (a/2) - (b/6)

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NOTE: use property of equality to isolate <em>b</em> from <em>a</em>

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-(a/2) - (a/2)

NOTE: continue to use property of equality to isolate <em>a</em><em> </em>from <em>b</em>

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3 years ago
kiyo bought a pizza for 12.75 and four medium drinks to Pauli’s pizza. Define a variable and write an expression to represent th
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The total cost, if one drink costs $3 is $27.75

  • Let the cost of a pizza be x

  • Let the cost of a drink be y

If kiyo bought a pizza for 12.75 and four medium drinks to Pauli’s pizza, this expressed as x + 4y

Since a pizza costs $12.75, hence x = $12.75

The function becomes 12.75 + 5y

f(y) = 12.75 + 5y

To get the total cost if one drink costs $3, hence;

f(3) = 12.75 + 5(3)

f(3) = 12.75 + 15

f(3) = 27.75

Hene the total cost, if one drink costs $3 is $27.75

Learn more on function here: brainly.com/question/9418047

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2 years ago
A recent poll of 1500 new home buyers found that 60% hired a moving company to help them move to their new home. Find the margin
Mrac [35]

Answer:

The margin of error M.O.E = 2.5%

Step-by-step explanation:

Given that;

The sample size = 1500

The sample proportion \hat p = 0.60

Confidencce interval = 0.95

The level of significance ∝ = 1 - C.I

= 1 - 0.95

= 0.05

The critical value:

Z_{\alpha/2} = Z_{0.05/2} \\ \\  Z_{0.025} = 1.96 (From the z tables)

The margin of error is calculated by using the formula:

M.O.E = Z_{\alpha/2} \times \sqrt{\dfrac{\hat p(1 -\hat p)}{n}}

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M.O.E = 0.02479

M.O.E ≅ 0.025

The margin of error M.O.E = 2.5%

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