# How do you write a rule for the nth term of the arithmetic sequence given d=1/2, #a_5=20#?

##### 1 Answer

Jul 12, 2018

#### Explanation:

#"the n th term of an arithmetic sequence is"#

#•color(white)(x)a_n=a_1+(n-1)d#

#"we require to find "a_1#

#a_5=a_1+(4xx1/2)=20rArra_1=18#

#a_n=18+1/2(n-1)#

#color(white)(a_n)=18+1/2n-1/2#

#color(white)(a_n)=1/2n+35/2larrcolor(red)" n th term formula"#