Gọi 125.27+127.29+129.31+...+173.75125.27+127.29+129.31+...+173.75
là A, ta có
A=125.27+127.29+129.31+...+173.75A=125.27+127.29+129.31+...+173.75
⇒2.A=225.27+227.29+229.31+...+273.75⇒2.A=225.27+227.29+229.31+...+273.75⇒2.A=125−127+127−129+...+173−175⇒2.A=125−127+127−129+...+173−175⇒2.A=125−175⇒2.A=125−175
⇒2.A=275⇒2.A=275
⇒A=275÷2⇒A=275÷2
⇒A=175⇒A=175
KL: Vậy A =175