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Mathematics 15 Online
zarkam21:

Help

zarkam21:

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zarkam21:

B

zarkam21:

@Vocaloid

zarkam21:

because left would be the x-axis and going up would be the y axis

Vocaloid:

for parabolas written in this form, it's the opposite of what we normally expect 12y = x^2 y = (1/12)x^2 12(y+1) = x^2 becomes 12y + 12 = x^2 which becomes 12y = x^2 - 12 which becomes y = (12)(x^2 - 1) a downward shift, the opposite of what we expected from adding 1 to y so in order to shift 2 up, we need to subtract 2 from y and to shift right we need to subtract 1 from x so C not B

zarkam21:

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zarkam21:

I would just work with the 5 and -x right?

Vocaloid:

whenever you take the square root of something you get +A, - A, or 0, making the sum 0

zarkam21:

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Vocaloid:

first you have to double the second equation and eliminate the x^2 terms, then half the second equation to eliminate the y^2 terms, then you'll be left with y to solve for

zarkam21:

(-4,-3)

Vocaloid:

yeah nvm that's right

zarkam21:

Thanks

zarkam21:

0?

zarkam21:

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Vocaloid:

good

Vocaloid:

can we actually go back to this problem for a sec, I plugged in your answer and it didn't end up working :S

Vocaloid:

|dw:1517935602661:dw|

Vocaloid:

2x^2 + y^2 = 33 2x^2 + 2y^2 + 4y = 38 y^2 + 4y = 5 after we factor this we get y = 1 and y = -5, then we need to plug this back into the equation to get the possible x values

Vocaloid:

plugging in y = -5 gives x = -2, making the quadrant III solution (-2,-5)

zarkam21:

Okay thanks

zarkam21:

4?

zarkam21:

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Vocaloid:

good

zarkam21:

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zarkam21:

B

Vocaloid:

it's a parabola and a circle, so w/o doing any calculations the max is theoretically 4 not 3

Vocaloid:

parabola + an ellipse technically

zarkam21:

and 3 for this one right

zarkam21:

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Vocaloid:

yes

zarkam21:

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Vocaloid:

good

zarkam21:

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zarkam21:

B

Vocaloid:

good

zarkam21:

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Vocaloid:

solve the first equation for y y = 25 - x then plug this in for y into the first equation to solve for x

zarkam21:

(13,12)

Vocaloid:

good

zarkam21:

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zarkam21:

(4,3)

Vocaloid:

that's quadrant I

zarkam21:

sorry (4,-3)

Vocaloid:

good

zarkam21:

3

zarkam21:

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Vocaloid:

check again, how many times do the red lines/blue lines cross each other?

zarkam21:

4

Vocaloid:

good, so 4 solns not 3

zarkam21:

0?FR?

zarkam21:

0?

zarkam21:

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Vocaloid:

the first time I did this I used software and got 2,2, -2,-2 as the x-coordinates making the sum 0 we could also do it by hand if you want to confirm

zarkam21:

Yeah i did it an got 0 as well

zarkam21:

Lol wrong picture

Vocaloid:

subtracting the two eqn's gives us 4x^2 = 16 x = +/- 2 making 0 the sum :S

zarkam21:

yes so it is 0

Vocaloid:

yeah, 0

zarkam21:

(-2,3)?

zarkam21:

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Vocaloid:

quadrant I so both coordinates have to be positive

zarkam21:

(2,3))

Vocaloid:

good

zarkam21:

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zarkam21:

1. ellipse

Vocaloid:

good

zarkam21:

2. hyperbola 3.

Vocaloid:

you'd have to complete the square for #3 to figure out what shape it is

zarkam21:

3.circle

zarkam21:

oh it wouldn't be circle?

Vocaloid:

yeah it's a circle

zarkam21:

4. parabola 5. hyperbola

Vocaloid:

awesome, that's it

zarkam21:

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zarkam21:

\[center: (4,2) \]

zarkam21:

vertices (10,2)(-2,2)

zarkam21:

\[Foci: (4+\sqrt[3]{5},2)\]

zarkam21:

\[Foci: (4\sqrt[-3]{5},2)\]

zarkam21:

\[Eccentricity: \frac{ \sqrt{5} }{ 2 }\]

zarkam21:

\[assymptotes: y=\frac{ x }{ 2 }, y=-\frac{ x }{ 2 }+4\]

Vocaloid:

yeah so far so good (normally I would prefer to do the calculations by hand but it's pretty tedious tbh)

zarkam21:

Yeah no its fine i did 3 out 6 by hand

zarkam21:

I'm sure they are all correct

Vocaloid:

yeah I just checked and it looks fine

zarkam21:

length of transverse axis

zarkam21:

how do i find the length for the transverse axis and conjugate axis

Vocaloid:

the bigger denominator (36) is the a^2 value the smaller denominator (9) is the b^2 value transverse axis = 2a conjugate = 2b so transverse = 12 and conjugate = 6

zarkam21:

perfect thanks

zarkam21:

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zarkam21:

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zarkam21:

okay so i graphed it already, and got the center, vertices, and foci

zarkam21:

Need help with the eccentricity , major axis , and minor axis

Vocaloid:

major axis is double the square root of the bigger number so 2sqrt(16) = 2*4 = 8 minor axis is double the square root of the smaller denominator so 2sqrt(4) = 2*2 = 4 the minor axis is 4, which is under x so the minor axis is along the x-axis major axis is along the y-axis

zarkam21:

okay so major : 8 minor: 4

Vocaloid:

eccentricity = c/a a is the half length of the major axis (so a = 4) b is half the length of the minor axis (so b = 2) c^2 = a^2 - b^2 find eccentricity

zarkam21:

2^2

Vocaloid:

4^2 - 2^2 = ? remember exponents come first in pemdas

zarkam21:

16-4

zarkam21:

12

Vocaloid:

good, so c^2 = 12 and c = sqrt(12) or 2sqrt(3) so c/a = eccentricity = 2sqrt(3) / 4, or sqrt(3)/2

zarkam21:

\[\frac{ \sqrt{3} }{ 2 }\]

Vocaloid:

yeah, that

zarkam21:

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zarkam21:

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zarkam21:

for this i got everything except for focal chord

Vocaloid:

brb going to teach myself what the hell a focal chord is

zarkam21:

Lmao sure thing

Vocaloid:

alright what did you get for your p-value? b/c the focal chord is just 4p

zarkam21:

honestly i just figured out vertex, etc by online calculator

Vocaloid:

that's fine, we can just do a quick complete the square y^2 + 6y- 2x + 13 = 0 adding 9 to each side: y^2 + 6y + 9 - 2x + 13 = 9 (y+3)^2 = 2x - 4 = 2(x-2) then if y^2 = 4px then 4px = 2(x-2) making 4p = 2 and p = 1/2 making the focal chord 4p = 2 = your answer for focal chord

zarkam21:

Thank you so much

zarkam21:

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zarkam21:

I already got #10 , for some reason I'm not getting a correct answer for #11

Vocaloid:

gonna get back to this asap

zarkam21:

Sure take your time

Vocaloid:

alright, you can subtract equation 2 - equation 1 to get 2x + 4y + 12 = 0 dividing by 2: x + 2y + 6 = 0 so x = -2y - 6 then we can just plug this into the first equation to get y

Vocaloid:

x^2 + y^2 + 2x + 2y = 0 ( -2y - 6)^2 + y^2 + 2( -2y - 6) + 2y = 0 shoving this into a calculator gives us y = -12/5, y = -2 then we just plug back into equation 1 (one at a time) to find the matching x-values

Vocaloid:

it's a lot of algebra but I end up getting (-2,-2) and (-6/5, - 12/5) and they're both circles (since the question asks)

zarkam21:

Thank you so muchh

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