What is the first term in the sequence for which d = -2 and a7 = 3? a. -6 b. 12 c. 15 d. -12 select the best answer from the choices provided a) a b) b c) c d) d

Final answer is c. 15

Step-by-step explanation:

We need to find about what is the first term in the sequence for which d = -2 and a7 = 3

We will use nth term formula of arithmetic sequence.

we have been given a7 that means 7th term is 3

so plug n=7, d=-2 and a_n=3 into above formula

Hence final answer is c. 15

  about 5.6 days

step-by-step explanation:

we can fill the given information into the decay equation and solve for the value of t at which half the sample remains.

the half-life is about 5.6 days.