Calculate the first term of an arithmetical progression and the 

 common difference if the sum of the 24 terms of the A.P is 327

 and the sum of the 3 terms in the A.P is 383. Also, what is 

 the 30th term of this series. 

--> Produced by MATCAL Program 

--> The sum of the nth term in an A.P is given by the equation 

below 

--> S(n) = n / 2 [ 2a + ( n - 1 ) x d ] 

--> S(n) = Sum of the nth term,  n = number of terms, a = first 

term, d = common difference 

--> S(n) = 327, n = 24

--> 327 = 24 / 2 ( 2a  + ( 24 - 1 ) x d ) 

--> 327 = 12 ( 2a  +  ( 23)  x d ) 

--> 327 = 12 ( 2a  +  ( 23) d ) 

--> 327 = 24a + 276d 

--> 24a + 276d  = 327  eq ( 1 ) 

--> Produced by MATCAL Program 

--> The second equation is given below 

--> S(n) = 383, n = 3

--> 383 = 3 / 2 ( 2a  + ( 3 - 1 ) x d ) 

--> 383 = 1.5 ( 2a  +  ( 2)  x d ) 

--> 383 = 1.5 ( 2a  + 2d ) 

--> 383 = 3a + 3d 

--> 3a + 3d  = 383  eq ( 2 ) 

--> ------------------------------------------------------

--> 24a + 276d  = 327  eq ( 1 ) 

--> 3a + 3d  = 383  eq ( 2 ) 

-- > ------------------------------------------------------

--> Using Simultaneous equation of substitution method 

-- > 24a  + 276d   = 327 eq (1) 

-- > 3a  + 3d   = 383 eq (2) 

-- > 24a  = 327 - 276d  eq (3) 

--> Substitute eq(3) into eq(2) for a 

-- > a  = ( 327 - 276d ) / 24 eq (4) 

--> 3 x ( 327 - 276d ) / 24 + 3d = 383

--> 3 x ( 327 - 276d )  + 72d = 9192

--> 981 - 828d + 72d = 9192

--> -756d = 8211

--> d = 8211 / -756

--> d = -10.8611111111111

--> The common difference (d) = -10.8611111111111

--> From equation 4 above 

-- > a  = ( 327 - 276d ) / 24 eq (4) 

-- > Substitute the value of d into equation 4 to get a

-- > 24a  = ( 327 - 276 x 8211 / -756 )

-- > 24a  = ( 327 - 2266236 / -756 )

-- > 24a  = ( 327 + 2997.66666666667 )

--> a = 3324.66666666667 / 24

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--> a = 138.527777777778 

--> The first term of the A.P (a) = 138.527777777778

--> Produced by MATCAL Program 

-- > 

-----------End of simultaneous equation method---------------------

-->------------------- Using 2 X 2 matrix method------------------

-- >  [ 24  276   | 327 ] 

-- >  [ 3  3   | 383 ] 

--> 

--> Det = [ 24 x 3 - 3 x 276 ] 

--> Det = [ 72 - 828 ] 

--> Det = -756

--> 

--> a (first term) term is given below 

-- >  | 327  276   | 

-- >  | 383  3   | 

--> a = | 981 - 105708 | 

--> a = -104727

--> a = -104727 / -756

--> a = 138.527777777778

--> 

--> The common difference (d)is given below 

-- >  | 24  327   | 

-- >  | 3  383   | 

--> d = | 9192 - 981 | 

--> d = 8211

--> d = 8211 / -756

--> d = -10.8611111111111

--> 

--> Produced by MATCAL Program 

--> 

--> Nth term = a + ( n - 1 ) x d 

--> 30th term = 138.527777777778 + ( 30 - 1 ) x 

-10.8611111111111

--> 30th term = 138.527777777778 + ( 29 x 

-10.8611111111111 ) 

--> 30th term = 138.527777777778 + ( -314.972222222222 )

--> 30th term = -176.444444444444

--> 30th term of the series (A.P) = -176.444444444444

--> 

--> The first term is = 138.527777777778, the common 

difference (d) = -10.8611111111111

--> The required 30th term of the A.P series is = 

-176.444444444444

-->------------------- End of 2 X 2 matrix method ----------------

--> Produced by MATCAL Program 

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