The line x+ 2y = 9 intersects the curve xy + 18 = 0 at the points A and B. Find the coordinates of A and B.

Mathematics

1 answer:

victus00 [196]3 years ago

6 0

Subtracting the second equation by 18 on both sides, we have xy=-18. Next, we divide both sides by x to get y=-18/x Plugging that into the first equation, we have x+2(-18/x)=9. Multiplying both sides by x, we get x^2-36=9x. After that, we subtract both sides by 9x to get x^2-9x-36=0. Finding 2 numbers that add up to -9 but multiply to -36, we do a bit of guess and check to find the answers to be -12 and 3. Factoring it, we get
x^2-12x+3x-36=x(x-12)+3(x-12)=(x+3)(x-12). To find the x values, we have to find out when 0=(x+3)(x-12). This is simple as when you multiply 0 with anything, it is 0. Therefore, x=-3 and 12. Plugging those into x=-18/y, we get x=-18/y and by multiplying y to both sides, we get xy=-18 and then we can divide both sides by x to get -18/x=y. Plugging -3 in, we get -18/-3=6 and by plugging 12 in we get -18/12=-1.5. Therefore, our points are (-3,6) and (12, -1.5)

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In a recent year, 31% of all college students were enrolled part-time. If 8.6 million college students were enrolled part-time t

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A game is played with the following rules. Two ordinary number cubes, each with six sides labeled 1 to 6, are rolled. After each

Marysya12 [62]

Answer: - 0.28

Explanation:

1) Expected value: is the weighted average of the values, being the probabilities the weight.

That is: ∑ of prbability of event i × value of event i.

In this case: (probability of getting 2 or 12) × (+6) + (probability of gettin 3 or 11) × (+2) + (probability of any other sum) × (-1).

2) Sample space:

Sum              Points awarded

1+ 1 = 2            +6

1 + 2 = 3             +2

1 + 3 = 4             -1

1 + 4 = 5             -1

1 + 5 = 6             -1

1 + 6 = 7             -1

2 + 1 = 3             +2

2 + 2 = 4             -1

2 + 3 = 5             -1

2 + 4 = 6             -1

2 + 5 = 7             -1

2 + 6 = 8             -1

3 + 1 = 4             -1

3 + 2 = 5             -1

3 + 3 = 6             -1

3 + 4 = 7             -1

3 + 5 = 8             -1

3 + 6 = 9             -1

4 + 1 = 5             -1

4 + 2 = 6             -1

4 + 3 = 7         -1

4 + 4 = 8            -1

4 + 5 = 9            -1

4 + 6 = 10          -1

5 + 1 = 6            -1

5 + 2 = 7            -1

5 + 3 = 8            -1

5 + 4 = 9            -1

5 + 5 = 10          -1

5 + 6 = 11          +2

6 + 1 = 7            -1

6 + 2 = 8            -1

6 + 3 = 9            -1

6 + 4 = 10          -1

6 + 5 = 11          +2

6 + 6 = 12          +6

2) Probabilities

From that, there is:
- 2/36 probabilities to earn + 6 points.
- 4/36 probabilites to earn + 2 points
- the rest, 30/36 probabilities to earn - 1 points

3) Expected value = (2/36)(+6) + (4/36) (+2) + (30/36) (-1) = - 0.28

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2 years ago

Read 2 more answers

Please help me with this problem..

charle [14.2K]

Answer:

y = 6

Step-by-step explanation:

Given that y varies directly with x then the equation relating them is

y = kx ← k is the constant of variation

To find k use the condition y = 3 when x = 9, then

k = $\frac{y}{x}$ = $\frac{3}{9}$ = $\frac{1}{3}$ , thus