Réponse:
Développer
3x (a+5) = (a x 3x) + (5 x 3x)
7a (3-2a) = (3 x 7a) - (2a x 7a) = (3 x 7a) - 14a²
-2a (a+5) = (a x -2a) + (5 x -2a)
Factoriser
3xa + 3x5 = 3 (a+5)
4b + 16 = 4 (b+4)
7a² +2a = a (7a+2)
A
[tex] = \frac{2}{5} + \frac{3}{5} \times \frac{7}{3} [/tex]
[tex]= \frac{2}{5} + \frac{21 \div 3}{15 \div 3}[/tex]
[tex]= \frac{2}{5} + \frac{7}{5} = \frac{9}{5}[/tex]
B
[tex] = \frac{3}{4} + \frac{5}{4} \times \frac{2}{3} [/tex]
[tex] = \frac{3 \times 3}{4 \times 3} + \frac{10}{12} [/tex]
[tex] = \frac{9}{12} + \frac{10}{12} = \frac{19}{12} [/tex]
