a = 161
a+d = 154 , so d = -7
S(m) = (m/2)(2a + (m-1)d)
0 = m/2(322 - 7m+ 7)
329m - 7m^2=0
49m - m^2 = 0
m(49-m)=0
m = 49
the first and second terms of an arithmetic progression are 161 and 154 respectively.the sumthe first m terms is zero.find the value of m
2 answers
The answer will be 47.(329/7=47).