Question

22nd term: a1=5,d=4????

Answer 1

a1=5, =4*1+1 d=4
a2=5+4=9=4*2+1
a3=9+4=13=4*3+1
a4=13+4=17=4*4+1

a5=17+4=21=4*5+1

...
a22=4*22+1=83

do you see the mistake

Answer 2

The formula for arithmetic sequences is
a\/n= a\/1 + (n-1)d,
and n represents # of terms

With the information, we can make the equation:
a\/n= 5 + (n-1)(4) .
Then, since n= 22 in this particular problem, we can plug that number in.

a\/22 = 5 + (22-1)(4)
a\/22 = 5 + (21)(4)
a\/22 = 5 + (84)
a\/22 = 89

In conclusion, 89 is the value of the 22nd term