$$\:\frac{0.4}{2.5}\frac{\left(1\:\right)}{2.5}$$

$$4\sin^2\left(\frac{x}{2}\right)+8\cos\left(x\right)-7=0$$

$$\frac{\left(-1\right)^kx^k}{5^k}$$

$$\int\:\cos\left(ln\:t\right)\:dt$$

$$sinh^{-1}x$$

$$\frac{x^2+2x+4}{x^2}$$