Apprendre

a) $3x - 5 = 7$

$3x = 7 + 5$

$3x = 12$

$x = 4$

b) $2(x-3) = 4x + 2$

$2x - 6 = 4x + 2$

$2x - 4x = 2 + 6$

$-2x = 8$

$x = -4$

c) $\frac{x+1}{2} = \frac{2x-3}{3}$

On multiplie les deux membres par 6 (PPCM de 2 et 3) :

$3(x+1) = 2(2x-3)$

$3x + 3 = 4x - 6$

$3x - 4x = -6 - 3$

$-x = -9$

$x = 9$

d) $5 - 3(2x+1) = x - 4$

$5 - 6x - 3 = x - 4$

$2 - 6x = x - 4$

$-6x - x = -4 - 2$

$-7x = -6$

$x = \frac{6}{7}$