Bonjour,
a = 3(x-10)(x+10)+(2x+5)(x+10)
= (3x-30) (x+10) + 2x² +20x +5x +50
= 3x² +30x -30x -30 + 2x² +20x +5x +50
= 5x² +25x +20
b = (5x-9)²+(5x+10)(5x-9)
= 25x² - 90x +81 + 25x² -45x +50x -90
= 50x² -85x -9
c = (3x+4)²-25
= 9x² +24x +16 -25
=9x² +24x -9
b) Factoriser les expressions suivantes :
a= 3(x-10)(x+10)+(2x+5)(x+10)
= (x+10 ) (3x-30 +2x+5)
= (x+10) (5x -25)
b=(5x-9)²+(5x+10)(5x-9)
= (5x-9) ( 5x-9 +5x +10)
= (5x-9) ( 10x +1)
c=(3x+4)²-25
identité remarquable
=(3x+4 -5) ( 3x+4 +5)
= (3x-1) ( 3x+9)
