Bonjour
-11+8+6x²+2+6a+5-6x²
= 6x² - 6x² + 6a - 11 + 8 + 2 + 5
= 6a - 4
-4t+2×t²+t×(-3)×7×t
= - 4t + 2t² - 3t * 7t
= 4t + 2t² - 21t²
= - 19t² + 4t
-3x-7x²+2+5x²-1+3x-1
= - 7x² + 5x² - 3x + 3x - 1 - 1 + 2
= - 2x²
-7x-5+3x-2+6x²
= 6x² - 7x + 3x - 5 - 2
= 6x² - 4x - 7.
