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Linear Equations ( 6 to 10 ):
APTITUDE QUESTIONS (LINEAR EQUATIONS):
6. If a(x – a2) – b(x – b2) = 0, then x is equal to
A) (-a+b)(a2+ ab+b2)/(a+b)
B) a3+ b3/(a-b)
C) a3– b3/(a+b)
D) a2 + ab + b2
E) None of these
View Answer
Answer is D
Explanation:
ax – a3 – bx + b3 = 0
x = (a3– b3)/(a-b) = a2 + ab + b2
7. If 7x: 63 = 1:9, then x is equal to
A) 3
B) 2
C) 1
D) -1
E) None of these
View Answer
Answer is C
Explanation:
7x/63= 1/9 => x = 1
8. If 5 added to twice of a number it becomes 6, then the number is
A) 0.5
B) 5
C) 0.25
D) 0.05
E) None of these
View Answer
Answer is A
Explanation:
∵ 2x + 5 = 6
=> 2x = 1
=> x = 0.5
9. The sum of the two numbers is 11 and their product is 30, then the numbers are
A) 8, 3
B) 9, 2
C) 7, 4
D) 5, 6
E) None of these
View Answer
Answer is D
Explanation:
Let numbers be x and 11 – x
=> x(11 – x) = 30
=> (x – 5) (x – 6) = 0
=> x = 5, 6
10. If one number is thrice the other and their sum is 20, then the numbers are
A) 5, 15
B) 4, 12
C) 3, 9
D) 6, 18
E) None of these
View Answer
Answer is A
Explanation:
x + 3x = 20
=> x = 5