$$4x+y-7x-10y$$

$$h\left(x\right)=\left(x-x^{3}\right)^{5}\left(2x+3\right)^{7}$$

$$-3\cdot\left(-7\right)$$

$$\left(x^2-3y\right)\left(x^4+3x^2y+9y^2\right)$$

$$\lim_{x\to\infty}\left(\frac{3^x}{4^x}\right)$$

$$\cos^2\left(a\right)\cdot\sec^2\left(a\right)=1$$

$$\frac{2a^4-a^3-21a^2+7a+4}{2a^2+5a-4}$$