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Mathematics 8 Online
zarkam21:

Help please ? =)

zarkam21:

1 attachment
Vocaloid:

well part I just says to replace "sin(x)" with "u" so lmk what you get when you do that

zarkam21:

so just sin (u)?

Vocaloid:

not quite, "u" replaces the entire sin(x) expression so sin^2(x) becomes u^2

zarkam21:

2sin^2 x-5 u-3=0

Vocaloid:

almost, 2u^2 - 5u - 3 = 0 and that's it for part I

Vocaloid:

then for part II just factor 2u^2 - 5u - 3 = 0 like you normally would

zarkam21:

u=3,-1/2

Vocaloid:

good but I think part II only wants the factored form (u-3)(2u+1) = 0 as the sol'n then for part III go ahead and write down your two u values

Vocaloid:

then for part IV replace "u = 3" and "u = -1/2" with "sin(x) = 3 and sin(x) = -1/2" since they want you to replace u with sin(x)

zarkam21:

so sin(x) = 3 and sin(x) = -1/2 for part IV

Vocaloid:

yes

Vocaloid:

then for part V solve for x using the unit circle to see where sin(x) = -1/2 sin(x) = 3 does not have a solution since 3 is outside the range of sin

zarkam21:

so part V is just sin(x) = 3 does not have a solution since 3 is outside the range of sin

Vocaloid:

you also need to solve for sin(x) = -1/2

zarkam21:

7pi/6

Vocaloid:

good but there's one more

zarkam21:

11pi/6

zarkam21:

wait so these two answers for part V

Vocaloid:

good so your sol'ns for part V are 7pi/6 +/- 2pi *n and 11pi/6 +/- 2*pin

Vocaloid:

it wouldn't hurt to also include the part about sin(x) = 3 not having a sol'n

zarkam21:

\(\color{#0cbb34}{\text{Originally Posted by}}\) @Vocaloid then for part V solve for x using the unit circle to see where sin(x) = -1/2 sin(x) = 3 does not have a solution since 3 is outside the range of sin \(\color{#0cbb34}{\text{End of Quote}}\)

Vocaloid:

yeah that

zarkam21:

yeah thats what I was going to ask would i include that statement in part V or IV

zarkam21:

I'll go with part V ^^

Vocaloid:

yeah it's part V

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