what are the 9 theory

Question: Answer: To find the two middle terms: Since n = 9, the two middle terms are ..

Question: Find four numbers in AP whose sum is 26. Sum of the products of the extremes and the middle terms is 62. Answer: Let (a - 3d), (a - d), (a + d), (a + 3d) be the four numbers in AP The numbers are ..

Two numbers are in the ratio 3:4. If 8 is added to the numbers, the ratio becomes 5:6. Find the number..

Divide Rs.256 in the ratio 7:9..

Factorise 5x 2 - 9x - 1..

i) 1 + 4 + 7 + 10 + ... is a series in which first term is 1, second term is 4, third term is 7 and so on. ii) 3 - 9 + 27 - 81 + ... is also a series in which the first term is 3, second term is -9, third term is 27 and so ..

Verify by actual multiplication. Verification by actual multiplication: ..

Recall the following identities for finding the products: Observe that the LHS in the identities are all factors and the RHS are their products. Thus, we can write the factors as follow..

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