FeedBack Form

Your Name :
Your Email :
Your Location :
Your Message :
   
FeedBack

SURDS AND INDICES PROBLEMS

SURDS AND INDICES -> IMPORTANT FACTS AND FORMULAE

1. LAWS OF INDICES :
  (i) am * an = am + n
  (ii)  am / an = am - n
  (iii)  (am)n = amn
  (iv)  (ab)n = anbn
  (v)  (a/b)n = an/ bn
  (vi)  a0 = 1
2. SURDS : Let a be rational number and n be a positive integer such
that a(1/n) = na
3 LAWS OF SURDS :
  (i)  na = a (1/n)
  (ii)  nab = na x nb
  (iii)  na/b = na / nb
  (iv)  (na)n = a

SURDS AND INDICES -> EXAMPLES

1. What is the quotient when (x-1 - 1) is divided by (x - 1)?
  Sol. x-1 - 1 / x-1 - (1/x)-1 / x-1 = (1-x)/x =(1-x)/x * 1/(x-1) = -1/x.
Hence, the required quotient is - 1/x
2. If 2x-1 + 2x+1 = 1280, then find the value of x
  Sol. 2x-1 + 2x+1 = 1280 ⇔ 2x-1(1+2x) = 1280
⇔ 2x-1 = 1280/5 = 256 = 28x-1 = 8 ⇔ x = 9.
Hence, x = 9.
3. If [1/5]3y = 0.008, then find the value of (0.25)y
  Sol. [1/5]3y = 0.008 = 8/1000 = 1/125 = [1/5]3 ⇔ 3y = 3 ⇔ y = 1.
∴ (0.25)y = (0.25)1 = 0.25.
Hence, the required distance is 6 km.

SURDS AND INDICES -> EXERCISE

13. If 3x - 3x-1 = 18, then the value of xx is
 
  • A. 3
  • B. 8
  • C. 27
  • D. 36
Ans: C.
Sol.
3x - 3x-1 = 18
⇔ 3x-1 (3 - 1) = 18
⇔ 3x-1 = 9
⇔ 32
⇔ x-1 = 2
⇔ x = 3.
∴ xx = 33 = 27.
 
14. The value of [(10)150 ÷(10)146] is
 
  • A. 1000
  • B. 10000
  • C. 100000
  • D. 1000000
Ans: B.
Sol.
(10)150 ÷(10)146 = (10)150 / 10146
= (10)(150 - 146) = 104 = 10000.
 
 
15. (2.4*103) / (8*10-2)=?
 
  • A. 3*104
  • B. 3*105
  • C. 3*10-4
  • D. 3*10-5
Ans: A.
Sol.
(2.4 * 103) / (8*10-2) = 2.4*103 / 8*10-2 = 24*10/8*10-2
= (3*104).