Bonjour,
ex1
A = 4/7 -2/7 *5/3
A = 4/7 - 10/21
A = 12/21-10/21
A = 2/21
B = (2+4/9) / ( 1/2 -2/3)
B = ( 18/9 +4/9) / ( 3/6 - 4/6)
B = ( 22/9 ) / ( -1/6)
B = 22/9 * (-6/1)
B = - 3*2 * 11*2 / 3*3
B = - 44 /3
C = ( 16 *3²*10^(-2) ) / ( 27*2³ *10^(-3)
C = ( 16*9 * 10^(-2) / ( 27* 8 *10^(-3)
C = ( 144*10^(-2) ) / ( 216*10^(-3) )
C = ( 12* 10^(-2) / 18 * 10^(-3) )
C = ( 2*10^(-2) / 3*10^(-3)
C = 2/3 * 10^(-2)/ 10^(-3)
C = 2/3 * 10^1
C = 2/3 * 10
C = 20/3
ex2 :
1) 25 - 64x² = ( 5 +8x) ( 5-8x)
2) (5-8x) ( 5+8x) - (5x-4) (5+8x) = (5+8x) ( 5-8x - 5x+4) = (5+8x) ( -13x+9)
3) (5+8x ) (-13x+9) = 0
2 solutions : 5+8x = 0 et -13x +9 = 0
8x = -5 -13x = -9
x = -5/8 x = 9/13
