Question

The 12th term of the arithmetic sequence is 10.5. The 18th term of this sequence is 13.5. Find the common difference and the first term

Answer 1

Answer:

common difference is 0.5

first term is 5

Step-by-step explanation:

use the formula for the nth term of an ap Tn=a+(n-1)d

T12=10.5

T18=13.5

therefore come up with two equations

T12=a+(12-1)d

10.5=a+11d(1st equation)

T18=a+(18-1)d

13.5=a+17d(2nd equation)

then solve both as a simultaneous equation

a+11d=10.5

a+17d=13.5

-6d/-6=-3/-6

d=0.5

use one of the equations to find the first term

a+11(0.5)=10.5

a+5.5=10.5

a=10.5-5.5

a=5

I hope this helps

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