So sánh A= 1+2+262+...+2^4 và B=2^5-1
Giải thích
A=1+2+22+...+24
2A=1.2+2.2+22.2+...+24.2
2A=2+22+23+...+25
2A−A=2+22+23+...+25−1+2+22+...+24
A=2+22+23+...+25−1−2−22−...−24
A=25−1
Vậy A=B
A=1+2+22+...+24
2A=1.2+2.2+22.2+...+24.2
2A=2+22+23+...+25
2A−A=2+22+23+...+25−1+2+22+...+24
A=2+22+23+...+25−1−2−22−...−24
A=25−1
Vậy A=B