Question

The fourth term of a sequence is 18.
The term-to-term rule is: 'Subtract 3 then multiply by 3.
What is the first term of the sequence?​

Answer 1

Answer:

let Ist term be x

and 2nd term be y

and 3rd term be z.

NOW, according to ques,

y=(x-3)3 --------eq1

z=(y-3)3

z=[(x-3)3-3]3 --------eq2 (using eq1)

Now

18=(z-3)3

18={[(x-3)3-3]3-3}3 (using eq2)

6=[(x-3)3-3]3-3

9=[(x-3)3-3]3

3+3=(x-3)3

2=x-3

x=5

hence answer is 5.

DONT FEAR WITH CALCULATION.

Answer 2

Answer:

$\frac{ \sqrt{ \frac{ {3 { = = 169 \times - - - \frac{ { { {y { { {?}^{2} }^{2} }^{?} }^{2} \times \frac{?}{?} }^{2} }^{2} }{?} \times \frac{234}{?} }^{?} }^{2} }{?} } }{?} \times \frac{?}{2}$