Sagot :
Bonjour ;
a = 50 - (x + 20)
= 50 - x - 20
= 30 - x .
b = - (10 + x) + (x + 5)
= - 10 - x + x + 5
= - 5 .
c = (x² - 4x) - (5x² + 2x - 1)
= x² - 4x - 5x² - 2x + 1
= - 4x² - 6x + 1 .
d = - (3 - x + x²) + (- 2x + 3x² - 8)
= - 3 + x - x² - 2x + 3x² - 8
= 2x² - x - 11 .
e = x - 4 - (2 + x) + (x + 5)
= x - 4 - 2 - x + x + 5
= x - 1 .
f = - (x - 8 + (x - 6) - (7-x) : il manque une parenthèse .
Je suppose qu'on a : f = - (x - 8) + (x - 6) - (7-x)
= - x + 8 + x - 6 - 7 + x
= x - 5 .
g = (x² + 5x - 4) - (- 2x² + 9x - 7)
= x² + 5x - 4 + 2x² - 9x + 7
= 3x² - 4x + 3 .