Which is greater: √5 + √7 or √3 + √9?
Both pairs add to 12 under the roots (5 + 7 = 3 + 9).
For a fixed total, roots that are closer together give a larger sum.
√5 + √7 ≈ 2.236 + 2.646 = 4.882
√3 + √9 ≈ 1.732 + 3 = 4.732
Answer: √5 + √7
Square Roots & Cube Roots · Exercise 4 of 6
65 mixed-level square root and cube root questions in the style of IBPS/SBI ("√? = …"), SSC CGL/CHSL, RRB NTPC and Group D, UPSC CSAT, state exams and campus placements. Use them as a timed speed drill.
Which is greater: √5 + √7 or √3 + √9?
Both pairs add to 12 under the roots (5 + 7 = 3 + 9).
For a fixed total, roots that are closer together give a larger sum.
√5 + √7 ≈ 2.236 + 2.646 = 4.882
√3 + √9 ≈ 1.732 + 3 = 4.732
Answer: √5 + √7
If √x = 7 and ∛y = 3, find x − y.
√x = 7 → x = 49
∛y = 3 → y = 27
x − y = 22
Answer: 22
What will come in place of ? : (0.3)² + (0.4)² = (?)² (? positive)
0.09 + 0.16 = 0.25
? = √0.25 = 0.5
Answer: 0.5
If 1.4 × 1.4 = 1.96, find √1.96 + √0.0196.
√1.96 = 1.4
√0.0196 = 0.14
1.4 + 0.14 = 1.54
Answer: 1.54
What is the least perfect square that is exactly divisible by 2,700?
2,700 = 2² × 3³ × 5²
Only 3³ is unpaired → multiply by 3
2,700 × 3 = 8,100 = 90²
Answer: 8,100
∛0.125 + ∛0.064 = ?
∛0.125 = 0.5
∛0.064 = 0.4
0.5 + 0.4 = 0.9
Answer: 0.9
What will come in place of ? : √? + 14 = √2601
√2601 = 51
√? = 51 − 14 = 37
? = 37² = 1,369
Answer: 1,369
The product of a number and its square root is 343. What is the number?
x × √x = 343 → x^(3/2) = 7³
x = (7³)^(2/3) = 7² = 49
Check: 49 × 7 = 343
Answer: 49
If x = 1 + √2, find the value of x² − 2x.
x² − 2x = (x − 1)² − 1
x − 1 = √2 → (x − 1)² = 2
2 − 1 = 1
Answer: 1
Find √0.25 of 400.
√0.25 = 0.5
"of" means multiply: 0.5 × 400 = 200
Answer: 200
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