Q. Find the sum of the first 45 terms of the following series, to the nearest integer.2,7,12,…Answer:
Identify pattern: Identify the pattern in the series.The series starts at 2 and each term increases by 5. This is an arithmetic series with a common difference (d) of 5.
Find terms: Find the first term a1 and the common difference d of the series.The first term a1 is 2 and the common difference d is 5.
Use formula: Use the formula for the sum of the first n terms of an arithmetic series: Sn=2n×(2a1+(n−1)d). We need to find the sum of the first 45 terms, so n=45.
Substitute values: Substitute the values into the formula. S45=245×(2×2+(45−1)×5)
Perform calculations: Perform the calculations inside the parentheses first. S45=245×(4+44×5)
Multiply 44: Multiply 44 by 5. S45=245×(4+220)
Add 4: Add 4 to 220. S45=245×224
Multiply 224: Multiply 224 by 45 and then divide by 2. S45=2224×45
Perform multiplication: Perform the multiplication. S45=210080
Divide by 2: Divide 10080 by 2 to get the final sum.S45=5040