Q. (i) Find a formula for the sum S of any four consecutive odd numbers.(ii) Hence, find the value of S when the greatest odd number is −17 .
Define Odd Numbers: Let's denote the first odd number as n. Since odd numbers are 2 units apart, the next three consecutive odd numbers would be n+2, n+4, and n+6.
Calculate Sum Formula: To find the formula for the sum S of these four consecutive odd numbers, we add them together: S=n+(n+2)+(n+4)+(n+6).
Simplify Formula: Simplify the formula by combining like terms: S=4n+12.
Find Value of n: Now, we need to find the value of S when the greatest odd number is −17. Since the greatest number in our sequence is n+6, we set n+6=−17.
Solve for n: Solve for n: n=−17−6.
Calculate n: Calculate n: n=−23.
Substitute n into Formula: Now that we have the value of n, we can find S by substituting n into our formula S=4n+12.
Calculate S: Calculate S: S=4(−23)+12.
Simplify Calculation: Simplify the calculation: S=−92+12.
Final Calculation: Final calculation for S: S=−80.