Bonjour
2)
A = 3 (2x² - 6x - 4) - (5x - x² - 4)
A = 6x² - 18x - 12 - 5x + x² + 4
A = 6x² + x² - 18x - 5x - 12 + 4
A = 7x² - 23x - 8
B = 1 - 5 (z² + 8z - 4) + 3 (z² - 2z + 10)
B = 1 - 5z² - 40z + 20 + 3z² - 6z + 30
B = - 5z² + 3z² - 40z - 6z + 1 + 20 + 30
B = - 2z² - 46z + 51.
3)
J = (3/4 - 5/6) - [7/2 - (3/5 - 2)]
J = [(3 x 3) / (4 x 3) - (5 x 2) / (6 x 2)] - [(7 x 5) / (2 x 5) - [(3 x 2) / (5 x 2) - (2 x 10 / (1 x 10)]]
J = (9/12 - 10/12) - [35/10 - (6/10 - 20/10)]
J = - 1/12 - (35/10 - (- 14/10)
J = - 1/12 - (35/10 + 14/10)
J = - 1/12 - 49/10
J = (- 1 x 5) / (12 x 5) - (49 x 6) / (10 x 6)
J = - 5/60 -294/60
J = - 299/60
