Question

I need help !!!!!!!! Can you help me??????

Answer 1

Answer:

69

Step-by-step explanation:

Hey there! To find the 20th term of arithmetic sequence, we can do by using general terms.

General Term - Arithmetic

$\displaystyle \large{a_n = a_1 + (n-1)d}$

where a_n is nth term, a_1 is the first term and d is our common difference.

We know the first term which is 12 and we want to find the 20th term which is our desired term.

Hence, the equation is $\displaystyle \large{a_{20} = 12+(20-1)d}$

However, we don’t know the value of d yet which is common difference. To find the common difference, we can do by subtracting next term with previous term.

15-12 = 3

18-15 = 3

21-18 = 3

If we keep doing it, we’ll always get 3. Therefore, 3 is our common difference.

$\displaystyle \large{a_{20}=12+(19)3}\\\displaystyle \large{a_{20}=12+57}\\\displaystyle \large{a_{20}=69}$

Thus, the 20th term is 69.

If you have any questions, let me know through the comment!

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