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3 years ago

6x - 5y = 70 7x + 2y = 66

Mathematics

1 answer:

Scilla [17]3 years ago

7 0

Answer:

(10,-2) x=10 y=-2

Step-by-step explanation: I used substitution

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34kurt

70% of the student would walk to school

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4 years ago

Read 2 more answers

Express (8 - 3sqrt(2))/(4 + 3sqrt(2)) in the form of a + b * sqrt(2) where a and b are integers.

Naya [18.7K]

Answer: $\boldsymbol{-25+18\sqrt{2}}$

The expression is in the form $a+b\sqrt{2}$ where a = -25 and b = 18

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Work Shown:

Let $x = 3\sqrt{2}$ and then square both sides

$x = 3\sqrt{2}\\\\x^2 = \left(3\sqrt{2}\right)^2\\\\x^2 = \left(3\right)^2*\left(\sqrt{2}\right)^2\\\\x^2 = 9*2\\\\x^2 = 18\\\\$

We'll use both x and x^2 later on.

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The denominator is in the form 4+x. We'll multiply top and bottom by 4-x to then use the difference of squares rule. This will allow us to eliminate the square root in the denominator.

$\frac{8-3\sqrt{2}}{4+3\sqrt{2}}\\\\\frac{8-x}{4+x}\\\\\frac{(8-x)(4-x)}{(4+x)(4-x)}\\\\\frac{32-8x-4x+x^2}{16-x^2} \ \text{ difference of squares rule}\\\\\frac{32-12x+x^2}{16-x^2}\\\\$

$\frac{32-12*3\sqrt{2}+18}{16-18} \ \text{ plug in } x = 3\sqrt{2} \text{ and } x^2 = 18\\\\\frac{50-36\sqrt{2}}{-2}\\\\\frac{-2(-25+18\sqrt{2})}{-2}\\\\\boldsymbol{-25+18\sqrt{2}}$

Therefore,

$\frac{8-3\sqrt{2}}{4+3\sqrt{2}}=\boldsymbol{-25+18\sqrt{2}}$

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

Checking the answer:

Use a calculator to find that,

$\frac{8-3\sqrt{2}}{4+3\sqrt{2}} \approx 0.45584412271571 \\\\-25+18\sqrt{2} \approx 0.45584412271571$

We get the same decimal approximation, which helps confirm the correct answer.

Or you could use the idea that if M = N, then M-N = 0 to subtract the original expression M and the final result N. You should get 0 or very close to it.

3 0

3 years ago

A florist currently makes a profit of $20 on each of her celebration bouquets and sells an average of 30 bouquets every week. Sh

galina1969 [7]

We use the attached graph

a. The maximum profit is the y value that is the value of P(x) that reaches maximum. From the graph the maximum value of P(x) is 675

So the maximum profit the florist will earn from selling bouquets = $675

b. Break even is the point where the profit p(x) becomes 0

From the graph we can see that P(x) =0 at x= -10 and x=20

x=-10 is invalid

So, break even after 20 one- dollar decreases

c. The interval of number of one dollar decreases is where the profit P(x) is greater than 0.