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3 years ago

I really need help. Solving Systems with Substitution y=2x x+y=(-9)

Mathematics

1 answer:

Viktor [21]3 years ago

6 0

Answer:

Step-by-step explanation:

If you let y=2x, you can plug it into the other equation.

x+2x=-9

Then solve that equation.

3x=-9

x=-3

Then use y=2x to find y.

y=2(-3)=-6

y=-6

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A cookie recipe calls for 3 1/4 cup white sugar and 5/8 cup brown sugar.

Ostrovityanka [42]

Answer:

3.875

Step-by-step explanation:

because you add both of the sugars together

7 0

3 years ago

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

==========================================================

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.

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

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

2 years ago

How do you solve 6 1/4 x 2 7/11 =

Ivahew [28]

Answer:

16 and 21/44 or 725/44

Step-by-step explanation:

convert 6 and 1/4 into an improper fraction; 25/4

convert 2 and 7/11 into an improper fraction; 29/11

multiply them together. $\frac{25}{4}$ × $\frac{29}{11}$

you can do 25 × 29 to get 725

you can also do 4 × 11 to get 44.

725/44 simplifies to 16 and 21/44.

3 0

3 years ago

How do i figure this out???

Vladimir [108]

Theres 8 edges, 5 vertices, and 5 faces.

6 0

3 years ago

A number increased by 4 is the same as 19 minus 2 times the number

ElenaW [278]

Hello from MrBillDoesMath!

Answer:

n = 5

Discussion:

Let the original number be "n" Translating the problem statement to mathematical symbolism:

n + 4 = 19 - 2n => add 2n to both sides

n + 2n + 4 = 19 - 2n + 2n => combine like terms

3n + 4 = 19 => subtract 4 from both sides

3n = 19 -4 = 15 => divide both sides by 3

n = 15/3 =5

Check: Does 5 +4 = 19 - 2(5)? Does 9 = 9? Yes. so the value for n is confirmed correct.

Thank you,

MrB

6 0

3 years ago