Will give medal!! Please help!!

Find all solutions to the equation.

7 sin2x - 14 sin x + 2 = -5

Question

Will give medal!! Please help!!

Find all solutions to the equation.

7 sin2x - 14 sin x + 2 = -5

dschneider2016 · Answer

@mathstudent55  please help! Its super fast

dschneider2016 · Answer

@dumbcow @LoveIt

dumbcow · Answer

treat it like a quadratic equation
$$7u^2-14u +2 = -5$$
solve for "u"
then
$$\sin x = u$$
solve for x using inverse sine
$$x = \sin^{-1} u$$

anonymous · Answer

I'm not too good at math, still in pre-algebra :(

dschneider2016 · Answer

okay so would the next step be 7u^2−14u+7
u=1

dschneider2016 · Answer

@dumbcow

dschneider2016 · Answer

therefore sin x= 1 and to solve for x sin-1 (1) ?

dumbcow · Answer

good now plug  u = 1  into inverse sine function

or think what angles make sine = 1

dschneider2016 · Answer

90°

dumbcow · Answer

correct

dschneider2016 · Answer

okay so is that it?

dumbcow · Answer

depends on the domain given, for 0<x<360  thats it, one solution, x = 90

If they want all (infinite) solutions, then just add multiples of 360 to answer
--> 90 + 360n

dschneider2016 · Answer

So my answer is just 90 + 360n (on the assumption they want infinite solutions)?

dschneider2016 · Answer

@dumbcow

dumbcow · Answer

yes

dschneider2016 · Answer

Thanks so much! You're a life saver! @dumbcow

dumbcow · Answer

your welcome :)