bonjour;
A = (5x - 1) ² + (5x - 1)(x + 3)
1. Développer et réduire A.
= 25x² -10x +1 +5x² +15x -x -3
= 30x² +4x -2
2. Calculer A pour x = 4/5
30*(4/5)² +4*4/5 -2
= 30* 16/25 + 16/5 -2
= 480/25 +16/5 -2
= 480/25 +16/5*5/5-2*25/25
= 480/25 + 80/25 -50/25
= 510/25
= 102/5
= 20,4
