Krishna
0

Step 1: Note down the given terms, and write their equivalent term of the arithmetic sequence.

            EXAMPLE: 18th term = a + (n-1)d = a + (18 - 1)d

                                              = a + 17d

                                21th term = a + 20d

Step 2: Set up equations according to the equivalent terms of arithmetic sequence.

            NOTE: Equate the given terms with the equivaent terms of arithmetic sequence. This will form the equations.

             EXAMPLE: 18th term = 25

                                a + 17d = 25.................................(1)

                                21st term = 32.5

                                a + 20d = 32.5...............................(2)

                              

Step 3: Solve these equations (linear equations) to get the unknown values

            NOTE: Solve the linear equations

                        1) Substitution method, 2)Cross-multiplication, 3)Elimination method


Step 4: Compare these values with the given values.