1+6+11+16+......+x=148Find x if they are in ap

1.	1+6+11+16+......+x=148Find x if they are in ap
Answer» a= 1d=6-1 =5Sn=148148 = n/2 [2a +(n-1)d]Now putting the values of a and d148= n/2[1+(n -1 )5]148=n/2[1+5n-5]396=5n^2 -4n5^n - 4n - 396Then solve this by the formula discriminate D=b^2 - 4acx= -b+&-√D/2a.......Thanku...

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