Simplification
- If the product of four consecutive natural numbers increased by a natural number p, is a perfect square; then the value of p is
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1× 2 × 3 × 4 = 24
⇒ 24 + 1 = 25 = 52 ;
2 × 3 × 4 × 5 = 120
⇒ 120 + 1 = 121 = 112
∴ P = 1Correct Option: D
1× 2 × 3 × 4 = 24
⇒ 24 + 1 = 25 = 52 ;
2 × 3 × 4 × 5 = 120
⇒ 120 + 1 = 121 = 112
∴ P = 1
- If x is a perfect square integer such that 7 < (2x – 3) < 17, then the value of x is :
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Check through options When x = 9,
2x – 3 = 2 × 9 – 3 = 15 < 17Correct Option: C
Check through options When x = 9,
2x – 3 = 2 × 9 – 3 = 15 < 17
- The sum of the squares of two positive integers is 100 and the difference of their squares is 28. The sum of the numbers is :
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Let the numbers be x and y.
Then,
x2 + y2 = 100 ...(i)
x2 – y2 = 28 ...(ii)
On adding,
2x2 = 128
⇒ x2 = 64 ⇒ x = 8
From equation (i),
64 + y2 = 100
⇒ y2 = 36 ⇒ y = 6
∴ Required sum
= 8 + 6 = 14Correct Option: C
Let the numbers be x and y.
Then,
x2 + y2 = 100 ...(i)
x2 – y2 = 28 ...(ii)
On adding,
2x2 = 128
⇒ x2 = 64 ⇒ x = 8
From equation (i),
64 + y2 = 100
⇒ y2 = 36 ⇒ y = 6
∴ Required sum
= 8 + 6 = 14
- If the sum and difference of two numbers are 20 and 8 respectively, then the difference of their squares is :
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Let x + y = 20 and
x – y = 8
∴ (x + y) (x – y) = 20 × 8
⇒ x2 – y2 = 160Correct Option: D
Let x + y = 20 and
x – y = 8
∴ (x + y) (x – y) = 20 × 8
⇒ x2 – y2 = 160
- The number, whose square is equal to the difference between the squares of 975 and 585, is :
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Let the required number be x.
As per given information,
x2 = (975)2 – (585)2
⇒ x2 = (975 + 585) (975 – 585)
⇒ x2 = 1560 × 390
⇒ x = √1560 × 390
= √13 × 12 × 3 × 13 × 10 × 10
= 780Correct Option: A
Let the required number be x.
As per given information,
x2 = (975)2 – (585)2
⇒ x2 = (975 + 585) (975 – 585)
⇒ x2 = 1560 × 390
⇒ x = √1560 × 390
= √13 × 12 × 3 × 13 × 10 × 10
= 780