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MCR3U
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Unit 4 – Exponential Functions Date: 4.4 Simplifying Algebraic Expressions Involving Exponents
Homework: Practice Problems and Pages 235-‐237: Questions #1-‐9{every other}, 10-‐12 14, 15 Learning Objectives/Success Criteria: At the end of this lesson I will be able to:
• Simplify expressions before evaluating algebraic expressions by substitution • Solve for an unknown variable within an exponential expression
Ms. Choo’s MCR3U class has been locked in a heated debate as to the answer to −3× −3 :
• Winston says the numbers under the radical sign can be multiplied so the negatives cancel out with −3× −3 = 9 =3 . By convention, the positive real root is given.
• Yathavan says −3× −3 is the same as −3( )2which can be rewritten as −3( )
12"
#$
%
&'2
. According to the
power rule, the exponents can be multiplied and −3( )12"
#$
%
&'2
simplifies to (−3)1 or -‐3.
• William says that −1 is equal to the imaginary number i and i2 =−1 . Therefore, −3 can be rewritten as −1× 3 or i 3 and −3× −3 = i 3× i 3 = 3( )
2i2 =−3 .
Which argument(s) are correct? Example 1: Simplify
a) −1( )2 b) −12× −3 c) −3
−9 d) −4 × −5 e) −4 × 5
Steps to Solving Exponential Equations:
1. If the bases are not the same, change bases to a common base. 2. Simplify if necessary 3. Equate the exponents and solve for the unknown. 4. Perform a check
Example 2: Solve for x
a) 52x−1 = 1125 b) 34x+2 =27x−2 c) 362x+14 = 1296x
d) 25x −30(5x )+125=0 e) 32x+1 −10(3x )+3=0 f) 4x +4x+1 =40 Practice: Solve each equation.
a) 27= x32 b) m
34 =27 c) x−
32 =
1729 d) 7= r
12
e) v54 =243 f) n
32 =125 g) (n−27)
32 =64 h) 26=−1+(27x)
34
i) 3125=(−1−18p)53 j) 5=3+4a−
16 k) −x
32 =−27 l) −54=10−(m−10)
32
m) −5126=−6−5(3x+22)53 n) 9+5 2m3 =29 o) 3646=1+5(4r+17)
32
p) −646=−3(65−n)32 +2 q) −3+(8−2x)
54 =29
Answers: a) 9 b) 81 c) 81 d) 49 e) 81 f) 25 g) 43 h) 3 i) -‐7 j) 64 k) 9 l) 26 m) 14 n) 32 o) 16 p) 29 q) -‐4