Difference 5867

Calculate the value of the first term and the difference in the arithmetic sequence

a1 + a7 = 42
a10-a3 = 21

Correct answer:

a =  12
d =  3

Step-by-step explanation:


a+(a+6d) = 42
(a+9d) - (a+2d) = 21

a+(a+6·d) = 42
(a+9·d) - (a+2·d) = 21

2a+6d = 42
7d = 21


d = 21/7 = 3
a = 42-6d/2 = 42-6 · 3/2 = 12

a = 12
d = 3

Our linear equations calculator calculates it.



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