Question

simplifique a expressão 20 - (3×+2) . (3×-5)
O resultado é:
a) 9x²-9 x- 10
b) 9x²+9x+30
c)-9 x² +9x+30
d) -9ײ+9×

Answer 1

Letra C.

$20 - (3x + 2) \: . \: (3x - 5) \\ \\ 20 - (9x {}^{2} - 15x + 6x - 10) \\ \\ 20 - (9x {}^{2} - 9x - 10) \\ \\ 20 - 9x {}^{2} + 9x + 10 \\ \\ 30 - 9x {}^{2} + 9x \\ \\ \boxed{\boxed{\boxed{ - 9x {}^{2} + 9x + 30 }}}$