# CE1D Like n°8

Résous les équations suivantes :

• $5x + 9 = 18 + 2x$
• $7x - 2 = 2 - 3x + 20$
• $9 \cdot (3x + 2) = 3 \cdot (5x + 6)$
• $-5 \cdot (2x + 5) = 3 - (2x + 9)$
Voir la solution

 $5x + 9 = 18 + 2x$$5x + 9 = 18 + 2x$ $5x - 2x = 18 - 9$$5x - 2x = 18 - 9$ $3x = 9$$3x = 9$ $x = 9 : 3$$x = 9 : 3$ $x = 3$$x = 3$ $7x - 2 = 2 - 3x + 20$$7x - 2 = 2 - 3x + 20$ $7x + 3x = 2 + 20 + 2$$7x + 3x = 2 + 20 + 2$ $10x = 24$$10x = 24$ $x = 24 : 10$$x = 24 : 10$ $x = 2,4$$x = 2,4$ $9 \cdot (3x + 2) = 3 \cdot (5x + 6)$$9 \cdot (3x + 2) = 3 \cdot (5x + 6)$ $27x + 18 = 15x + 18$$27x + 18 = 15x + 18$ $27x - 15x = 18 - 18$$27x - 15x = 18 - 18$ $12x = 0$$12x = 0$ $x = 0 : 12$$x = 0 : 12$ $x = 0$$x = 0$ $-5 \cdot (2x + 5) = 3 - (2x + 9)$$-5 \cdot (2x + 5) = 3 - (2x + 9)$ $-10x - 25 = 3 - 2x - 9$$-10x - 25 = 3 - 2x - 9$ $-10x + 2x = 3 - 9 + 25$$-10x + 2x = 3 - 9 + 25$ $-8x = 19$$-8x = 19$ $x = \dfrac{-19}{8}$$x = \dfrac{-19}{8}$

90 vues