$$2-5\left(1\right)$$

$$\left(-100\right)+\left\{\left[\left(678\right)-\left(276\right)+9\right]\right\}$$

$$4a^2+25b^2-20ab$$

$$\left(5x+2y+3z\right)^2$$

$$\int_6^{\infty}\left(\frac{9}{-x+x^2}\right)dx$$

$$\frac{\cos\left(4x\right)+4\cos\left(2x\right)+3}{8}$$