Starting from the formula

We can divide all the angles by 2 and we get

And finally

Angle x is a third quadrant angle, meaning that it is somewhere between 180 and 270. This implies that x/2 lies between 90 and 135. So, x/2 is a second quadrant angle, and its cosine is negative. This means that we can update the previous equation to

You know that

so, plug that value into the expression and you'll get cos(x/2).
Well if he has 9 then eats one that would have 8 so they both would get 4
Hope it helped! :)
And cool pic
Answer:
that is dependent event when you are taking out first marble permanently

$\implies 2^{2x}-2\cdot5^{2x}-(2^x)(5^x)>0$
let $2^x=a$ and $5^x=b$
So, $a^2-2b^2-ab>0$
divide by $b^2$, ($b^2>0$)
$\implies \left(\frac ab\right)^2-\left(\frac ab\right) -2>0$
this is a quadratic, in $\left(\frac ab\right)$, let it be $x$
So, $x^2-x-2>0$
Can you simplify it now?
Answer:
x=5/3 or 1.67
Step-by-step explanation:
6x+5=15
6x=10
x=10/6
x=5/3