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Do Now: 4.5 Practice C
 r
A  P 1  
 n
nt
The formula above gives the amount of money
A in an account after t years if the annual
interest rate is r (in decimal form), n is the
number of times interest is compounded per
year, and P is the original principle. What
interest rate is required to earn $7 in two
months if the principle is $500 and the interest
rate is compounded monthly?
 r
A  P 1  
 n
nt
12(1 6 )
r 

507  5001  
 12 
Check : 8.4% is the rate
for the 12 month period,
2
r 

507  5001  
 12 
2
r 

1.014  1  
 12 
r
1.014  1 
12
0.084  r or r  8.4%
so each month the bank is
calculatin g 0.7% interest.
Check : 500.007   3.50
503.5(.007)  3.52  503.50  507.02
Academy Algebra II
4.6: Imaginary Numbers
HW: p.279 (4-10 even), p.282 (85-90 all)
Test 4.1-4.6: Friday, Oct. 3rd
Imaginary Numbers
i  1
i  1 because   1    1   1  1
2
2
i  i because   1   1  i  i
3
3
i 1
4
because
  1
4
  1  1  1
 Therefore
i i
i i
i  1
i  1
i  i
i  i
i 1
i 1
1
2
3
4
5
6
7
8
Simplify
1.)
2.)
3.)
i
15
i
44
i
51
Solve the equation
1.)
x  36
2.)
3x  40   x  56
2
2
2
Solve the equation
3.)  5( x  3)
2
 10
Academy Algebra II
4.6: Imaginary Numbers
HW: p.279-280 (12-32 even)
Test 4.1-4.6: Friday, Oct. 3rd
Complex Numbers in Standard Form
Standard Form: a  bi
 Write the expression as a complex
number in standard form.

(Practice B evens)
1.)
(1  i )  (3  i )
2.)
(4  i )  (4  5i )
3.)
 2i (3  i )
Simplify: (Practice B evens)
1.)
( 2  i )( 4  2i )
2.)
(5  2i )(5  2i )
Simplify: (Practice B evens)
3.)
 2i(1  i )( 2  3i )
4.)
(2  i )
2
Practice B (evens): Write the expression as a
complex number in standard form.
1.) 4  3i
7i
5
2.) 3  2i
Practice B (evens): Write the expression as a
complex number in standard form.
3.)
1  2i
2 i