1) 3,4 * 5c = 17c
2) 7,5a * 2x = 15ax
3) - c³ * 3c⁴ = - 3c⁷
4) 2x⁶y * (- 4x²y⁷) = - 8x⁸y⁸
5) (- 4a³b)² = 16a⁶b²
6) (7y)² = 49y²
7) 2m⁶ + 5m⁶ + 8m⁶ - 11m⁶ = 4m⁶
8) 9x²y + x²y - 13x²y - 9x²y = - 12x²y
9) (- 4y²)³ * 2y⁵ = - 64y⁶ * 2y⁵ = - 128y¹¹
10) 3t² - 5t² - 11t² - 3t² + 5t² = - 11t²