五期

(2) A surd of any order may be transfumed inta

a sund of a

PENETAKKY

WAH KIU YAT PO

# B

1768

#

英文

rey

数單科

(109)

你您絡交

different order

Surds of different anders may be transformant

into surd's of the same avdler.

} (4) (ab)* *a*. 6x

i's

A surd which is expressed so that the infegei under the root sign is as small as possible said to be in its simplest fo

form:/

MATHEMATICS (14)

LESSON 14 INDICES AND LOGARITHM

§A, Indices and Surds:

¿B, LOGARIZHM:

We are familiar with the following laws i

<i>

a" ÷ a" =

am-n

(2")"= Q.

Ya* = (Ya} .fro

aq o

can be expressed in the form A“, s.4. AT=N;

If number N then, X is called the logarithm of the no. N, to base 0. NATATION :

X une

Logan

The following are the main properties of logaritheo . If a is a non-negative number such that ask 1, then

at is always positive, for all x ( x may be -'me, o or 've). Hence, it is meaningless to say log. of a

-'re number

log. of zero.

</a>

af

a

= Va

770

J

2

EXAMPLE 1 Simplify and express with positive indices:

(a) 524 (517-2

3,

loga! Log, a=!

= 0

*

Log (MN)=

・log. M + log!

3

(0) 1.4 20 125 ÷ 2.5

SOLUTION A

<a>

Exp. = 5

*

5

<b>

Exp.

= 5 #5454

-3

5*f

பதி

20

for any non - zero

a.

5, loga () = logam ~logan.

*; Log. (N*=* Log.M; for any/h (+'ve, - 've, a, faction)

Log A/N == log. N

er integer

NOTE: <> Log, MI log. Not tog (mzm)

<2>

ley Log M

-alog.n

<3> loom + logo M-

Log

das from property 5, when Mul, Log = log. Na cologn

<5> Logarithm to base to is called commen logarithm. NOTATION: Log, Nal

more general loz N=x

which is most used if practical calculation,

was introduced by English

and

ematician

*RARE!

日二月二年八六九一度公年七十五届中

用,纖係由:

還透對中有

南大

今關討

秋問

ЯЗНАЯ

ང་ན

東南亞高等教育機構協會

今明在港會議

關問題 並擬訂交換學生辦法 以備 討論東南亞五十間大學交換學生之有

今秋開始實施

**

能加

備有

Ext

0. if xo.

3

-(#)×(÷) + (2±)

= 2.71240

Natural

retical mathewmedier.

Mahleaticas.

log49)

Wher

is called

ogarithm

() () (룿)

x

- () () ()

-

Example &· if x = a

+

(~1)

prove that *40 (44* - 3)

and cut Napit

"EXAMPLE 2: Simplif

SOLUTION (*** Exp.

Prest

22000 A+

I" (a - J.

3

HONG

Example 21 SOLUTION

2

— za3 + 2(32)√ā**7)*

2 Q3 + 6 a { a2-1)

=20(40*-34

Solve √+6 +/+ = √2+7

{√x+6 +/+) =

62 + 7

6 x + 7 4X

(x+2) ( x − ) = 0

Checking, (a, when

X - 3

x

1258-118-1

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一般甘灣緒帶二百元,者注意

[雙百元,三批五十

-

<b>

HINTS & AM. To E11

az (62 - 43*

«*» (a*~¿” + abi a*- 4* — ab)

«e» (X+1) 1293) EX ̃– $2+ Q)

<f> 20°($Q+ 4) { 30−2} {#Q*++).

«J» (x=7) (2x+550x-2)

Noth Apply Remainder Themem do 1974

10 - 21x-10= (52+2}{42 −5)

het F(x)=100x^+ 10x+p, tika F°° 3)=8&j= c

by Exp.

3(Log2)

Satlogs)

Log +21 (og 5)

($) + log # ̈‚„X”

(.log

(Long

(Loy

BRARY

10

* Log 10°

following relation.

gitar) + log, 4.

J

KOK

4. S. =/X+6 +/7+T

#√3+6 + £7

A 3 + 2 = 5

R.S. NG*3+7= 5

(b) when * --

~ 4. S. ==

-√5{ + SE1

-+-

ALLE, MA. S

SOLUTION.

-4+

R.S=√6(-4)+7 =B ---- LSAR.S A is NOT a solution of the equation © This shows the importance, in checking)

EXAMPLE *: Rationalise -

Saamzima Exp. =7

ANS

log (27+1) - loyal - Loga

σ

loyal-224) = log. 1=loy a

(

ay

A

uy arty

_{X*+1) ("*+a)= daly

EXAMPLE 7 : if a'r b=7a6, then log at b = 1⁄2 (loga + log bì

PRODE: 書

a2 + 5+ cab rab+zab

(a+b)= gab

#

kog (a+b)" = Lig(4ab)

Log (a+b) =

log at log b + log 4

or log(a+b)= ±( log at Log b) + 1 6og 9 Log (a + b) -

log 5=

3 = = { lag a + Lag b} log Att ! ( log a + . (og b)

J** *** **

< Ахау уакустика,

4-xy ther

(1) (y-1) = 0

But

2-1

*+ y +2 = x+xy = 1

Zie

4 = 1.

EXERCISA 14

Find the meaning and value of a", where a mo .

2, Simplify and express with positive indices ›

225 x 72" x 1000

<A>

3, 14 x

+

find the wahre of

5

EXAMPLE &

Solve

= 21.

nth

}

- √3 + E + !

2-274

4 - (242**

2.5+ 2/T + 4/+6

=-{176 + 5 + 25 +

perfect Pack (0) If A is a rational number and is not a

then I is called a sued of the power, nth order. ce.g. fe is a quadrats sund) Hence, surds are inexpressible wither as integen or as fraction, but the value of a surd can be obtaineït to any degree of accuracy.tn.g, mn festational number )

alstien: Take logarithms for both sides ( to base 10):

log (6*** 3** - *}m log 21

Log 21

(3x+1) Log 6+ (15x-2) log 3 =

log 21-logh + 2 logs ( 3 Log 6 + 15 Log 3) x =.

Log 21 - log b + 2 logs

3 ing to + 15 Log "

X =

43222-0:2782 +0.9542

3 x 2.77 +15 40.4477

LELEL

{ car to 2 Mac, ɔ

4 Given

m = 3 +2/,

7=8-25.

find

(A) MA

and (c) m'ent

5, Solve the following equations

"

- x

2

cb √42^+172 + 15

−√2x^ + 52- 3 = · 2 x *— 12x = 18; Given log 2 =0.30103, log 3 = 0.47712, obtain approximate values of the logarithms to base 10, of (as Log 2.5. (b) log 15 and (e) log 0.12

7. Solve

(log(x − y) + Log (7x - 8 y) = 2

Log (23+y+) = log(x^~29 + y2)m } .

$, Solve 0.93o m 1.832

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