How Do You Simplify Conjugate Expressions?

AI Thread Summary
The discussion focuses on simplifying conjugate expressions involving complex numbers. The first expression, (-7+20)(-10-3i), was correctly simplified to 76+i using the FOIL method. For the second expression, (-2-5i)/(3+4i), the correct result was found to be (-26-7i)/25 after applying the rules for division with imaginary numbers. Participants confirmed the accuracy of both solutions and shared tips on handling complex numbers. Overall, the conversation provided clarification and support for simplifying these expressions.
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1) (-7+20)(-10-3i)

2) (-2-5i)/(3+4i)

I don't think I did these two questions right does anyone know how?
 
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Multiply with 1, written in terms of the conjugate expressions of the denominators.
 
I simplified (-7+2i)(-10-3i) and got 76+i is this correct?
 
yes, that is correct.
 
1) (-7+20)(-10-3i)

Step 1.) FOIL the Problem
Step 2.) Simplify from there (Do addition Subtraction etc.)

2) (-2-5i)/(3+4i)

I forgot how to do division with imaginary numbers :eek: I'll try to look it back up and give you some help
 
All you need to know to solve these sort of problems is that:
i=\sqrt{-1}
i^2 = -1
i^3 = -i
i^4 = 1 and the cycle repeats

so to take your question:
(-7+2i)(-10-3i)
70+21i-20i-6i^2
76+i

you did in fact do it correctly.
 
hey, for that latex all i have 2 do is put [-code-] the code and end. Correct?
let me try.
seems i have 2 put latex
\theta
 
Last edited:
HawKMX2004 said:
1) (-7+20)(-10-3i)

Step 1.) FOIL the Problem
Step 2.) Simplify from there (Do addition Subtraction etc.)

2) (-2-5i)/(3+4i)

I forgot how to do division with imaginary numbers :eek: I'll try to look it back up and give you some help

Thanks for taking the time to look it up, and thanks everyone who told me the first one is right what a relief! :eek: For simplifying (-2-5i) / by (3+4i) I got (-26-7i)/25 as my final answer can someone tell me is this right? :frown:
 
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yes you are right again
(-2-5i)/(3+4i) does equal (-26-7i)/25
 
  • #10
Yay!

vladimir69 said:
yes you are right again
(-2-5i)/(3+4i) does equal (-26-7i)/25

Thanks sooo much! :-p If anyone has any objections they may still speak :smile:
 
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