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3 years ago

Y = 5x - 13 4x + 3y = 18

1 answer:

3 0

replace Y = 5x - 13
into
4x + 3y = 18



4x + 3 (5x - 13) = 18
4x + 15 - 39 = 18
4x -24 = 18
4x = 18 +24
4x = 42
x = 42/4
x = 10.5

Y = 5(10.5) - 13
= 52.5 - 13
= 39.5

answer: x = 10.5 and y = 39.5

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find the centre and radius of the following Cycles 9 x square + 9 y square +27 x + 12 y + 19 equals 0

Citrus2011 [14]

Answer:

Radius: $r =\frac{\sqrt {21}}{6}$

$Center = (-\frac{3}{2}, -\frac{2}{3})$

Step-by-step explanation:

Given

$9x^2 + 9y^2 + 27x + 12y + 19 = 0$

Solving (a): The radius of the circle

First, we express the equation as:

$(x - h)^2 + (y - k)^2 = r^2$

Where

$r = radius$

$(h,k) =center$

So, we have:

$9x^2 + 9y^2 + 27x + 12y + 19 = 0$

Divide through by 9

$x^2 + y^2 + 3x + \frac{12}{9}y + \frac{19}{9} = 0$

Rewrite as:

$x^2 + 3x + y^2+ \frac{12}{9}y =- \frac{19}{9}$

Group the expression into 2

$[x^2 + 3x] + [y^2+ \frac{12}{9}y] =- \frac{19}{9}$

$[x^2 + 3x] + [y^2+ \frac{4}{3}y] =- \frac{19}{9}$

Next, we complete the square on each group.

For $[x^2 + 3x]$

1: Divide the $coefficient\ of\ x\ by\ 2$

2: Take the $square\ of\ the\ division$

3: Add this $square\ to\ both\ sides\ of\ the\ equation.$

So, we have:

$[x^2 + 3x] + [y^2+ \frac{4}{3}y] =- \frac{19}{9}$

$[x^2 + 3x + (\frac{3}{2})^2] + [y^2+ \frac{4}{3}y] =- \frac{19}{9}+ (\frac{3}{2})^2$

Factorize

$[x + \frac{3}{2}]^2+ [y^2+ \frac{4}{3}y] =- \frac{19}{9}+ (\frac{3}{2})^2$

Apply the same to y

$[x + \frac{3}{2}]^2+ [y^2+ \frac{4}{3}y +(\frac{4}{6})^2 ] =- \frac{19}{9}+ (\frac{3}{2})^2 +(\frac{4}{6})^2$

$[x + \frac{3}{2}]^2+ [y +\frac{4}{6}]^2 =- \frac{19}{9}+ (\frac{3}{2})^2 +(\frac{4}{6})^2$

$[x + \frac{3}{2}]^2+ [y +\frac{4}{6}]^2 =- \frac{19}{9}+ \frac{9}{4} +\frac{16}{36}$

Add the fractions

$[x + \frac{3}{2}]^2+ [y +\frac{4}{6}]^2 =\frac{-19 * 4 + 9 * 9 + 16 * 1}{36}$

$[x + \frac{3}{2}]^2+ [y +\frac{4}{6}]^2 =\frac{21}{36}$

$[x + \frac{3}{2}]^2+ [y +\frac{4}{6}]^2 =\frac{7}{12}$

$[x + \frac{3}{2}]^2+ [y +\frac{2}{3}]^2 =\frac{7}{12}$

Recall that:

$(x - h)^2 + (y - k)^2 = r^2$

By comparison:

$r^2 =\frac{7}{12}$

Take square roots of both sides

$r =\sqrt{\frac{7}{12}}$

Split

$r =\frac{\sqrt 7}{\sqrt 12}$

Rationalize

$r =\frac{\sqrt 7*\sqrt 12}{\sqrt 12*\sqrt 12}$

$r =\frac{\sqrt {84}}{12}$

$r =\frac{\sqrt {4*21}}{12}$

$r =\frac{2\sqrt {21}}{12}$

$r =\frac{\sqrt {21}}{6}$

Solving (b): The center

Recall that:

$(x - h)^2 + (y - k)^2 = r^2$

Where

$r = radius$

$(h,k) =center$

From:

$[x + \frac{3}{2}]^2+ [y +\frac{2}{3}]^2 =\frac{7}{12}$

$-h = \frac{3}{2}$ and $-k = \frac{2}{3}$

Solve for h and k

$h = -\frac{3}{2}$ and $k = -\frac{2}{3}$

Hence, the center is:

$Center = (-\frac{3}{2}, -\frac{2}{3})$

6 0

2 years ago

Fred brought 8 new baseball training cards to add to his collection .the next day his dog ate half of his collection there are n

ollegr [7]

Answer:

27 x 2 = 54

Step-by-step explanation:

3 0

3 years ago

5. Daniel arrives at his campsite out of breath from his swim and jog. His sister tells him that he should have swam to the boat

frosja888 [35]

Answer:

hello your question is incomplete attached below is the complete question

answer :

Daniels sister is not correct because the time that will be taken by Daniel will be greater than the initial total time taken by Daniel.

Step-by-step explanation:

First determine the time it will take Daniel to reach the Boat and the jogging time

time = distance / rate

where distance can be calculated using this equation: sin 53° = 400 / x

hence x ( distance ) = 500 ft

rate = 150

therefore Time ( t ) to reach boat = 500 / 150 = 3.33 minutes

Time for jogging ( as calculated ) = 3.69 minutes

therefore total time taken by Daniel = 3.33 + 3.69 = 7.02 minutes

Finally determine if Daniel's sister is correct that he should have swam to the boat ramp and then jogged

lets assume Distance to swim = x ( according his sister )

determine the value of x = $\sqrt{400^2 + 1400^2 }$ therefore X = 1456.02 feet

∴

Total time to be taken if Daniel follows his sister's instruction = 1456.02 / 150 = 9.71 minutes

Daniels sister is not correct because the time that will be taken by Daniel will be greater than the initial total time taken by Daniel.

6 0

3 years ago

Radon went to America on holiday . She took 750 USD Dollars with her to spend

Alex777 [14]

Answer:

Step-by-step explanation:

4 0

1 year ago

Define powers provide an example of power with an exponent of 2

shtirl [24]

Well not sure what you are asking, but If it is what I think it is, it would go like this:
2
(9^2)

Then the answer should be

9^4 since we multiply the exponents.

If you mean this...

3^2....It would be same as 3 x 3 which we should know is equal to nine.

Hope I helped! (Be sure to thank me!)

7 0

3 years ago

Read 2 more answers