SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x =...

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SOLVING LOGARITHMIC AND INDICES PROBLEM

Transcript of SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x =...

Page 1: SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x = 27 = 3 3 By comparing index: 2x = 3 If a x = a y then.

SOLVING LOGARITHMIC AND INDICES PROBLEM

Page 2: SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x = 27 = 3 3 By comparing index: 2x = 3 If a x = a y then.

Solving equation in the form of ax = ay

Example:

32x = 27 = 33

By comparing index:

2x = 3

If ax = ay then x = y

23x

Page 3: SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x = 27 = 3 3 By comparing index: 2x = 3 If a x = a y then.

Examples

8x+1 = 4x+3

(23)x+1 = (22)x+3

23x+3 = 22x+6

By comparing index: 3x + 3 = 2x + 6 3x – 2x = 6 – 3 x = 3

Page 4: SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x = 27 = 3 3 By comparing index: 2x = 3 If a x = a y then.

9x. 3x1 = 243

32x. 3x1 = 35

32x + (x 1) = 35

33x1 = 35

By comparing index, 3x – 1 = 5 3x = 6 x = 2

Examples

Page 5: SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x = 27 = 3 3 By comparing index: 2x = 3 If a x = a y then.

SOLVE 2X + 2X+3 = 32

See the right way ---->

A very different example. 2X + 2X+3 = 25

x + x + 3 = 5 2x = 2 x = 1WARNING! WARNING! WARNING!The solution above is WRONG!!!

Page 6: SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x = 27 = 3 3 By comparing index: 2x = 3 If a x = a y then.

2x + 2x 23 = 32Factorize 2x

2X(1 + 23) = 322X (9)= 322X = 32/9X lg 2 = lg 32 – lg 9X (0.3010)= 1.5051-0.9542

X=1.8302

SOLVE 2X + 2X+3 = 32

Page 7: SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x = 27 = 3 3 By comparing index: 2x = 3 If a x = a y then.

INDEX EQUATION WITH DIFFERENT BASEIf we cannot express both sides of the equation with the same base, we solve the equation by taking logarithms on both

sides.

Example

5 x = 6Taking logarithms on both sides.

log10 5 x = log10 6

x log10 5 = log10 6

x (0.6990) = 0.7782 x = 0.7782 0.6690 x = 1.113

Solving equation in the form of ax = b,where a ≠-1, 0 , 1

Page 8: SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x = 27 = 3 3 By comparing index: 2x = 3 If a x = a y then.

Example: Solve 5x – 3x+1 = 0Solution:

5x – 3x+1 = 0 5x = 3x+1

Taking logarithms on both sides,

lg 5x = lg 3x+1

x lg 5 = (x + 1) lg 3

x lg 5 = x lg 3 + lg 3

x lg 5 – x lg 3= lg 3

x(lg 5 – lg 3)= lg 3

x(0.6990 – 0.4771) = 0.4771

x = 2.150

Page 9: SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x = 27 = 3 3 By comparing index: 2x = 3 If a x = a y then.

Solving Logarithmic EquationSolve log5 (5x – 4) = 2 log5 3 + log5 4

First, simplify the right hand side.

log5 (5x – 4) = log5 3

log5 = log5

Comparing number in both sides.

log5 log5

5x = 40

x = 8

(5x – 4 ) (36)

2 + 4log

55

(5x – 4) == (36)

Page 10: SOLVING LOGARITHMIC AND INDICES PROBLEM. Solving equation in the form of a x = a y Example: 3 2x = 27 = 3 3 By comparing index: 2x = 3 If a x = a y then.

Solve the equation log5 x = 4 logx 5

Solution:

log5 x = 4

log5 x. log5 x = 4

(log5 x)2 = 4

log5 x = 2 or -2

x = 52 or 5 2

xlog15

(Change base from x to 5)