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24 Surds and Indices PYQ (Solutions)

Master Surds and Indices for CAT 2026 with practice questions and detailed explanations

CAT 2025

Surds & Indices (irrational roots, exponent rules) are another minor algebra topic. CAT questions on surds/indices are infrequent and usually simple if they appear. They often come intertwined with other problems (like simplifying an expression within a larger algebra question).

  • The combined category of “Logarithms, Surds and Indices” contributed about 1–2 questions in many years.
    • For instance, CAT 2019 had maybe one question using indices (since “Modern Math” was only 1 question total that year).
    • CAT 2020 saw up to 4 questions involving logs/surds in one slot (slot 1) but only 1 in another, indicating volatility.
  • Many papers had 0 direct surd questions.

Summary: Surds/indices are not a guaranteed yearly feature – they appeared sporadically (often bundled with logs). When they do appear, usually 1 question at most in a given slot.

Weightage Over Past Years

YearQ.NODifficulty Level
20255Hard
20245Medium
20234Hard
20221Hard
20211Medium
20202Medium
20193Hard
20181Hard
20172Medium

CAT 2025 Surds and Indices questions

Question 1

Slot-1

For any natural number kk, let ak=3ka_k = 3^k. The smallest natural number mm for which

(a1)1×(a2)2××(a20)20<a21×a22××a(20+m)\left(a_1\right)^1 \times \left(a_2\right)^2 \times \cdots \times \left(a_{20}\right)^{20} < a_{21} \times a_{22} \times \cdots \times a_{(20+m)}

is

59
56
58
57

Question 2

Slot-2

The sum of digits of the number ( ( 625 ) ^ { 65 } \times ( 128 ) ^ { 36 } ), is

Question 3

Slot-2

If ( 9 ^ { x ^ { 2 } + 2 x - 3 } - 4 \left( 3 ^ { x ^ { 2 } + 2 x - 2 } \right) + 27 = 0 ), then the product of all possible values of ( x ) is

\( 5 \)
\( 20 \)
\( 30 \)
\( 15 \)

Question 4

Slot-3

If (x2+1x2)=25\left(x^2 + \dfrac{1}{x^2}\right) = 25 and x>0x > 0, then the value of (x7+1x7)\left(x^7 + \dfrac{1}{x^7}\right) is

$44859\sqrt{3}$
$44856 \sqrt { 3 }$
$44853 \sqrt { 3 }$
$44850 \sqrt { 3 }$

Question 5

Slot-3

If 1212x×424x+12×52y=84z×2012x×2433x612^{12x} \times 4^{24x+12} \times 5^{2y} = 8^{4z} \times 20^{12x} \times 243^{3x-6}, where x,yx, y and zz are natural numbers, then x+y+zx+y+z equals

CAT 2024 Surds and Indices questions

Question 1

Slot-1

The sum of all real values of kk for which (18)k×(132768)13=18×(132768)1k\left(\frac{1}{8}\right)^k \times\left(\frac{1}{32768}\right)^{\frac{1}{3}}=\frac{1}{8} \times\left(\frac{1}{32768}\right)^{\frac{1}{k}} , is

$\frac{2}{3}$
$-\frac{2}{3}$
$\frac{4}{3}$
$-\frac{4}{3}$

Question 2

Slot-1

If (a+bn)(a+b \sqrt{n}) is the positive square root of (29125)(29-12 \sqrt{5}), where aa and bb are integers, and nn is a natural number, then the maximum possible value of (a+b+n)(a+b+n) is.

22
6
18
4

Question 3

Slot-2

If (x+62)12(x62)12=22(x+6 \sqrt{2})^{\frac{1}{2}}-(x-6 \sqrt{2})^{\frac{1}{2}}=2 \sqrt{2} , then xx equals

Question 4

Slot-3

The sum of all distinct real values of xx that satisfy the equation 10x+410x=81210^x + \frac{4}{10^x} = \frac{81}{2}, is

$2 \log_{10} 2$
$3 \log_{10} 2$
$4 \log_{10} 2$
$\log_{10} 2$

Question 5

Slot-3

If (a+b3)2=52+303(a+b \sqrt{3})^2=52+30 \sqrt{3} , where aa and bb are natural numbers, then a+ba+b equals

7
10
8
9

CAT 2023 Surds and Indices questions

Question 1

Slot-1

If 5x+9+5x9=3(2+2)\sqrt{5 x+9}+\sqrt{5 x-9}=3(2+\sqrt{2}) , then 10x+9\sqrt{10 x+9} is equal to

$4 \sqrt{5}$
$2 \sqrt{7}$
$3 \sqrt{31}$
$3 \sqrt{7}$

Question 2

Slot-2

The sum of all possible values of xx satisfying the equation 24x222x2+x+16+22x+30=02^{4x^2} - 2^{2x^2 + x + 16} + 2^{2x + 30} = 0 is

$\frac{3}{2}$
$\frac{5}{2}$
$\frac{1}{2}$
3

Question 3

Slot-3

Let nn and mm be two positive integers such that there are exactly 41 integers greater than 8m8^m and less than 8n8^n , which can be expressed as powers of 2 . Then, the smallest possible value of n+mn+m is

14
42
16
44

Question 4

Slot-3

If xx is a positive real number such that x8+(1x)8=47x^8 + \left(\frac{1}{x}\right)^8 = 47, then the value of x9+(1x)9x^9 + \left(\frac{1}{x}\right)^9 is

$40 \sqrt{5}$
$36 \sqrt{5}$
$30 \sqrt{5}$
$34 \sqrt{5}$

CAT 2022 Surds and Indices questions

Question 1

Slot-3

If (75)3xy=8752401\left(\sqrt{\frac{7}{5}}\right)^{3 x-y}=\frac{875}{2401} and (4ab)6xy=(2ab)y6x\left(\frac{4 a}{b}\right)^{6 x-y}=\left(\frac{2 a}{b}\right)^{y-6 x}, for all non-zero real values of aa and bb, then the value of x+yx+y is

CAT 2021 Surds and Indices questions

Question 1

Slot-3

If nn is a positive integer such that (107)(107)2(107)n>999(\sqrt[7]{10})(\sqrt[7]{10})^{2} \ldots(\sqrt[7]{10})^{n}>999 , then the smallest value of nn is

CAT 2020 Surds and Indices questions

Question 1

Slot-1

If x=(4096)7+43x = (4096)^{7+4\sqrt{3}}, then which of the following equals 64?

$\frac{x^{7/2}}{x^{4/\sqrt{3}}}$
$\frac{x^{7}}{x^{4\sqrt{3}}}$
$\frac{x^{7/2}}{x^{2\sqrt{3}}}$
$\frac{x^{7}}{x^{2\sqrt{3}}}$

Question 2

Slot-3

If a, b, c are non-zero and 14a=36b=84c14^{a} = 36^{b} = 84^{c}, then 6b(1c1a)6b\left(\frac{1}{c} - \frac{1}{a}\right) is equal to

CAT 2019 Surds and Indices questions

Question 1

Slot-1

If mm and nn are integers such that:

21934429m8n=3n16m644\frac{2^{19} \cdot 3^4}{4^2 \cdot 9^m \cdot 8^n} = \frac{3^n}{16^m \cdot \sqrt[4]{64}}

Then what is the value of mm?

-16
-24
-12
-20

Question 2

Slot-2

Question:

If 5x3y=134385^x - 3^y = 13438 and 5x1+3y+1=96865^{x-1} + 3^{y+1} = 9686, then x+yx+y equals [TITA]

Question 3

Slot-2

The real root of the equation 26x+23x+221=02^{6x} + 2^{3x+2} - 21 = 0 is

$\frac{\log_{2}3}{3}$
$$ \log_{2} 9 $$
$\frac{\log_{2}7}{3}$
$$ \log_{2} 27 $$

CAT 2018 Surds and Indices questions

Question 1

Slot-1

Given that x2018y2017=1/2x^{2018} y^{2017} = 1/2 and x2016y2019=8x^{2016} y^{2019} = 8, the value of x2+y3x^2 + y^3?

$\frac{37}{4}$
$\frac{31}{4}$
$\frac{35}{4}$
$\frac{33}{4}$

CAT 2017 Surds and Indices questions

Question 1

Slot-1

If 92x181x1=19449^{2x-1} - 81^{x-1} = 1944, then xx is

3
$\dfrac{9}{4}$
$\dfrac{4}{9}$
$\dfrac{1}{3}$

Question 2

Slot-2

If 9x1222x2=4x3×22x39^{x - \frac{1}{2}} - 2^{2x - 2} = 4^{x - 3} \times 2^{2x - 3}, then xx is

$\frac{3}{2}$
$\frac{2}{5}$
$\frac{3}{4}$
$\frac{4}{9}$

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