Question

A sequence contains the terms a2=17,a4=41,a7=77. Which formula represents the nth term of the sequence?
a. an=12n-7
b. an=-7n+12
c. an=12n+17
d. an=17n+12

Answer 1

Answer:

a. 12n-7

Step-by-step explanation:

a2=17

a+(2-1)d=17

a+d=17 ........(i)

a4=41

a+3d=41.......(ii)

subs eq. (i) from (ii)

a + 3d=41

a + d = 17

----------------

2d= 24

d=12

----------------

putting value of d in eq.(i)

a+(12)=17

a=5

NOW,

an=a + (n-1)d

=5+ (n-1)12

= 5 +12n-12

= 12n -7

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