The number is 30
100%=70 x%=21
Solve for the equation and it gets 30
I think 169 it would cost beacause 4×3=12 and
then 12×14=169
From the double-angle identity,
we can rewritte our given equation as:
By factoring 2cosx on the left hand side, we have
This equation has 2 solutions when
From equation (A), we obtain
and from equation (B), we have
On the other hand, we can find one more solution from the original equation by substituting x=0, that is,
then, x=0 is another solution. In summary, we have obtained the following solutions:
However, the intersection of the last set is empty. So the unique solution is x=0 as we can corroborate on the following picture:
Therefore, the solution set is: {0}
To find the percent, we do 5/25. That gives the decimal 0.2, to change that to a percent, we move the decimal point 2 places to the right and add a % sign, giving 20%