abcdg

a+b=10 =>(a+b)^2=100

=> a^2+b^2=100-2ab=100-2×21=100-42=58 Hay P=58

M=a^3+b^3=(a+b)(a^2-ab+b^2)=10(58-21)=10.37=370

Q=a^4+b^4=(a^2+b^2)^2-2a^2b^2=(a^2+b^2)^2-2(ab)^2=58^2-2.21^2=2482

C = 1/100 - 1/100.99 - 1/99.98 - 1/98.97 - ... - 1/3.2 - 1/2.1

C = 1/100 - (1/100.99 + 1/99.98 + 1/98.97 + ... + 1/3.2 + 1/2.1)

C = 1/100 - (1/1.2 + 1/2.3 + ... + 1/98.99 + 1/99.100)

C = 1/100 - (1 - 1/2 + 1/2 - 1/3 + ... + 1/98 - 1/99 + 1/99 - 1/100)

C = 1/100 - (1 - 1/100)

C = 1/100 - 99/100

C = -98/100 = -49/50

ko ai làm giúp mình , huhuhuhuhuhuhuhuhuhuhu

có ai giúp tôi ko