Réponse:
1.
MA=√[xM-xA)² + (yM-yA)²]
MA = √ [(x+3)² + (0-1)²]
MA = √[(x+3)² + 1]
MB = √[(xM-xB)² +(yM-yB)²]
MB = √[(x-1)² + (0-4)²]
MB = √[(x-1)² + 16]
2.
MA² = MB²
(x+3)²+1 = (x-1)² + 16
x² + 6x + 10 = x² - 2x + 17
6x + 10 = - 2x + 17
8x = 7
x = 7/8
3.
Les coordonnées du point M sont M(7/8; 0)
