Exercice 3.
Question 1.
[tex]5(x-3)-3x+7=5 \times x + 5 \times (-3) -3x + 7\\5(x-3)-3x+7=5x-15-3x+7\\5(x-3)-3x+7=2x-8[/tex]
Question 2.
[tex]5(x-3)-3x+7=9\\2x-8=9\\2x-8+8=9+8\\2x=17\\\dfrac{2x}{2}=\dfrac{17}{2}\\x=8,5[/tex]
Exercice 4.
Question 1.
[tex]2(x-7) = 2 \times x + 2 \times (-7)\\2(x-7) = 2x-14\\\\3(-x+1)=3 \times (-x) + 3 \times 1\\3(-x+1)=-3x+3[/tex]
Question 2.
[tex]2(x-7)=3(-x+1)\\2x-14=-3x+3\\2x-14+14=-3x+3+14\\2x=-3x+17\\2x+3x=-3x+17+3x\\5x=17\\\dfrac{5x}{5} = \dfrac{17}{5}\\x=3,4[/tex]
Exercice 5.
Développement.
[tex]7(6-2x)-3(4x+1)=7 \times 6 + 7 \times (-2x) -3 \times 4x -3 \times 1 \\7(6-2x)-3(4x+1)=42 - 14x - 12x - 3\\7(6-2x)-3(4x+1)=-26x+39[/tex]
Résolution de l'équation.
[tex]7(6-2x)-3(4x+1)=0\\-26x + 39 = 0\\-26x+39-39=0-39\\-26x=-39\\\dfrac{-26x}{-26} = \dfrac{-39}{-26} \\x = \dfrac{39}{26}\\x=1,5[/tex]
