Here you go let me know if you have questions
The double angle formula for the sine is

The right hand side is exactly your expression, where 
So, rewriting the expression from right to left, we have

<span>0.0001835 is the right answer after converting</span>
Hello :
<span>8x²+7x-3+4x-8 = 8x² +(7x+4x) +(- 3 - 8)=8x²+7x - 11</span>
(A)
Choice (B) is not the right answer because I
it's only 3rd order. But because f(x) goes to negative infinity when x goes to positive infinity means that the right answer is (A).