JAMIA 2022 — Mathematics PYQ
JAMIA | Mathematics | 2022The sum of 3 numbers in A.P. is -3, and their product is 8. Then sum of squares of the number is
Choose the correct answer:
- A.
9
- B.
10
- C.
21
(Correct Answer) - D.
12
21
Explanation
Step 1: Assume the Numbers
Let the three numbers be:
a−d,a,a+d
where a is the middle term and d is the common difference.
Step 2: Use the Sum Condition
The problem states that the sum of these three numbers is −3:
(a−d)+a+(a+d)=−3
Combining the terms, the d cancels out:
3a=−3
a=−1
Step 3: Use the Product Condition
The problem states that the product of these three numbers is 8:
(a−d)⋅a⋅(a+d)=8
Substitute a=−1 into the equation:
(−1−d)⋅(−1)⋅(−1+d)=8
Using the difference of squares identity (x−y)(x+y)=x2−y2:
−1⋅((−1)2−d2)=8
−1⋅(1−d2)=8
−1+d2=8
d2=9⟹d=±3
Step 4: Identify the Numbers
Using a=−1 and d=3 (or d=−3, the set remains the same):
-
First number: a−d=−1−3=−4
-
Second number: a=−1
-
Third number: a+d=−1+3=2
The three numbers are −4,−1, and 2.
Step 5: Find the Sum of Squares
The question asks for the sum of the squares of these numbers:
Sum=(−4)2+(−1)2+(2)2
Sum=16+1+4
Sum=21
Final Answer
The sum of the squares of the numbers is 21.

