1. (3x³y+2x²y²-8xy³) + (-9x³y-7x²y²-2xy³) =

2. (x³ + x² - 1x) + (¹x²³ - x² + x)

3. (0.4x³-0.7x² +0.5x)+(-0.8x³-0.9x²-0.8x)

4. (5x³-9x²-11x) + (-8x³-6x² + 7x) =

5. (24x-13x³+9x²+7) + (36x²+17x³-18x-35) =
6.
(26x³-45+28x-12x2)+(34-16x + 25x²-11x³) = ​