It is estimated that 15 workers can build a tower in 20 days. If only 10 workers are engaged for the job, then in how many days will the tower be built? 28 days 35 days 25 days 30 days

Describe all solutions of Ax=0 in parametric vector form, where A is row equivalent to the given matrix
$$\left[\begin{array}{cccc}1& 3& 0& -4\\ 2& 6& 0& -8\end{array}\right]$$

Find, correct to the nearest degree, the three angles of the triangle with the given vertices
A(1, 0, -1), B(3, -2, 0), C(1, 3, 3)

Whether f is a function from Z to R if 
a) ${\displaystyle f\left(n\right)=\pm n}$. 
b) ${\displaystyle f\left(n\right)=\sqrt{n^2+1}}$. 
c) ${\displaystyle f\left(n\right)=\frac{1}{n^2-4}}$.

How to write the expression $6^{\frac{3}{2}}$ in radical form?

How to evaluate ${\displaystyle \sin \left(\frac{-5\pi }{4}\right)}$?

What is the derivative of ${\cot }^{2}x$ ?

How to verify the identity: $\frac{\cos \left(x\right)-\cos \left(y\right)}{\sin \left(x\right)+\sin \left(y\right)}+\frac{\sin \left(x\right)-\sin \left(y\right)}{\cos \left(x\right)+\cos \left(y\right)}=0$?

Find $\tan \left(22.5^{\circ }\right)$ using the half-angle formula.

How to find the exact values of $\cos 22.5°$ using the half-angle formula?

How to express the complex number in trigonometric form: 5-5i?

The solution set of $\tan <!--\; \; -->\mathrm{\theta <!--\; \theta \; -->}=3\cot <!--\; \; -->\mathrm{\theta <!--\; \theta \; -->}$ is

How to find the angle between the vector and $x-$axis?

Find the probability of getting 5 Mondays in the month of february in a leap year.

How to find the inflection points for the given function ${\displaystyle f\left(x\right)=x^3-3x^2+6x}$?

How do I find the value of sec(3pi/4)?