A=x³-5x²
B=x²-11x+6
①A+2B
=x³-5x²+2(x²-11x+6)
=x³-5x²+2x²-22x+12
=x³-3x²-22x+12
②A+5B
=x³-5x²+5(x²-11x+6)
=x³-5x²+5x²-55x+30
=x³-55x+30
=-1+55+30
=84
A=x³-5x²
B=x²-11x+6
①A+2B
=x³-5x²+2(x²-11x+6)
=x³-5x²+2x²-22x+12
=x³-3x²-22x+12
②A+5B
=x³-5x²+5(x²-11x+6)
=x³-5x²+5x²-55x+30
=x³-55x+30
=-1+55+30
=84