Write in Standard Form (12+8x^3+3x-4x^2)+(5x^3+15-x+2x^2)

$(12 + 8 x^{3} + 3 x - 4 x^{2}) + (5 x^{3} + 15 - x + 2 x^{2})$

To write a polynomial in standard form, simplify and then arrange the terms in descending order.

$a x^{2} + b x + c$

Add $12$ and $15$ .

$8 x^{3} + 3 x - 4 x^{2} + 5 x^{3} + 27 - x + 2 x^{2}$

Add $8 x^{3}$ and $5 x^{3}$ .

$13 x^{3} + 3 x - 4 x^{2} + 27 - x + 2 x^{2}$

Subtract $x$ from $3 x$ .

$13 x^{3} + 2 x - 4 x^{2} + 27 + 2 x^{2}$

Add $- 4 x^{2}$ and $2 x^{2}$ .

$13 x^{3} + 2 x - 2 x^{2} + 27$

Move $2 x$ .

$13 x^{3} - 2 x^{2} + 2 x + 27$