bonjour
e) 10 (x+7) (x-5) = 3x (x+7)
10 (x+7) (x-5) - 3x (x+7) = 0
(x+7) (( x-5) *10 - 3x ) = 0
(x+7) ( 10x-50 -3x) = 0
(x+7) ( 7x-50) = 0
deux solutions : x+7 = 0 x = -7
7x-50 = 0
7x = 50
x = 50/7
f ) x² = 81
deux solutions X = 9 et X = -9
G) ( 7x-5)² = (2x+1)²
(7x-5)² - (2x+1)² = 0
(7x-5 +2x+1) ( 7x-5 -2x-1) = 0
( 9x -4) ( 5x-6) = 0
9x-4 = 0
9x = 4
x = 4/9
et 5x-6 = 0
5x = 6
x = 6/5