$\frac{d}{dx}7x^5+4y^4x^2=9$

$2b+8=b+18$

$\sin\left(x\right)\frac{dy}{dx}-2y\cos\left(x\right)=0$

$8x+10x-4xy-5y$

$cos\:30^{\circ}\:cos\:45^{\circ}\:-\:sin\:30^{\circ}\:sin\:45^{\circ}$

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

$\frac{\left(7x+3\right)}{2}-\frac{\left(9x-8\right)}{4}=6$