$\int\left(sen\:\frac{2x}{3}\right).dx$

$8x-3\frac{1}{2}y-9z+\left(7x-\left(-\frac{1}{2}y+2z-\left(-5\frac{1}{3}x-9y+5z\right)\right)-3z\right)$

$-z^2+y^2=x^2+25$

$\tan\left(x+y\right)=\frac{\cot\left(x\right)+cot\left(y\right)}{\left(cot\left(x\right)\cdot cot\left(y\right)\right)-1}$

$3^{2x}-6\cdot3^x+8=0$

$6x^2+3x-15$

$2x^2-3x+1.125$