Question

The fifth term of an arithmetic sequence is and the twelfth term is .
(a) Determine the values of the first term and the common difference.
(b) Obtain algebraically the value of for which Sn = -144

Answer 1

Answer:

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Answer 2

Answer:

a) d (common difference)= -4

a (first term)= 10

Step-by-step explanation:

a + (n-1)d

a+ 11d = -34

a+4d. = -6

solve the simultaneous equation

so 7d=-28

d= -4

substitute back into the equation

a+ (4x-4) = -6

a - 16 = -6

a=10