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This guide provides step-by-step solutions for equations in the form of ( ax = ay ) and explores various examples of solving logarithmic equations, indices problems, and using logarithms to simplify complex expressions. Key topics include equating indices, solving through logarithms, and handling different bases effectively. We’ll clarify common mistakes and provide corrective examples to enhance understanding. With practical applications and clear illustrations, this resource is invaluable for mastering logarithmic and indices equations.
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Solving equation in the form of ax = ay Example: 32x = 27 = 33 By comparing index: 2x = 3 If ax = ay then x = y
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
Examples 9x. 3x1 = 243 32x. 3x1 = 35 32x + (x 1) = 35 33x1 = 35 By comparing index, 3x – 1 = 5 3x = 6 x = 2
A very different example. SOLVE 2X + 2X+3 = 32 See the right way ----> 2X + 2X+3 = 25 x + x + 3 = 5 2x = 2 x = 1WARNING! WARNING! WARNING!The solution above is WRONG!!!
SOLVE 2X + 2X+3 = 32 2x + 2x 23 = 32 Factorize 2x 2X(1 + 23) = 32 2X (9)= 32 2X = 32/9 X lg 2 = lg 32 – lg 9 X (0.3010)= 1.5051-0.9542 X=1.8302
INDEX EQUATION WITH DIFFERENT BASE Solving equation in the form of ax = b,where a ≠-1, 0 , 1 If 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 = 6 Taking 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
Example: Solve 5x – 3x+1 = 0 Solution: 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
Solving Logarithmic Equation Solve 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. log5log5 5x = 40 x = 8 2 log5 4 + (5x – 4 ) (36) (5x – 4) = (36)
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 (Change base from x to 5)