a) P(x)+Q(x)=(x⁴ - 5x³ + 4x - 5) + ( -x⁴ + 3x² + 2x + 1 )

= x⁴ - 5x³ + 4x - 5 - x⁴ + 3x² + 2x + 1

=(x⁴-x⁴)- 5x³+3x²+(4x+2x)+(-5+1)

=-5x³+3x²+6x-4

Vậy P(x)+Q(x)=-5x³+3x²+6x-4

b) Ta có: P(x)=R(x)+Q(x)

Suy ra: R(x) =P(x)-Q(x)

(x⁴-5x³+4x-5)-(-x⁴+3x²+2x+1)

=x⁴-5x³+4x-5+x⁴-3x²-2x-1

=(x⁴+x⁴)-5x³-3x²+(4x-2x)+(-5-1)

=2x⁴-5x³-3x²+2x-6

Vậy R(x)=2x⁴-5x³-3x²+2x-6

a)24,3×(-11/25)+(-11/25)×75,7=

(-11/25)×(24,3+75,7)=(-11/25)×100

=-44

b)[(9²÷3²)+(125÷5²)]÷(-1/2)²

=[(3⁴÷3²)+(5³÷5²)]÷(-1/2)²

=[3²+5¹]÷(-1/2)²

=[9+5]÷(-1/2)²

=14÷(-1/2)²

=14÷(-1/4)

=-56

\(\dfrac{ }{ }\)\(\dfrac{ }{ }\)\(\dfrac{ }{ }\)\(\dfrac{ }{ }\)

c)\(\sqrt{ }\)16+\(\sqrt{ }\)100-\(\sqrt{ }\)36 

=\(\sqrt{ }\)4+\(\sqrt{ }\)10-\(\sqrt{ }\)6

=4+10-