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Mathematics 22 Online
OpenStudy (anonymous):

Find the real numbers x and y that make the equation true. -3 + yi = x + 6i

OpenStudy (nincompoop):

do you know what i stands for?

OpenStudy (anonymous):

no

OpenStudy (nincompoop):

well… do you know roots and radicals?

OpenStudy (anonymous):

Wait is it an imaginary number ?

OpenStudy (nincompoop):

yeahhhh, coocoobird! that is correct so do you know what is an imaginary number?

OpenStudy (anonymous):

Yes

OpenStudy (nincompoop):

so how come you're having trouble answering?

OpenStudy (anonymous):

I just wanted someone else to explain it to me

OpenStudy (nincompoop):

when you fully grasp what an imaginary number is, then we will solve your problem.

OpenStudy (mathteacher1729):

Answering this question boils down to understanding when two complex numbers are equal. There is no algebra involved, only definitions.

OpenStudy (anonymous):

Okay so it's not just imanginary numbers @mathteacher1729

OpenStudy (mathteacher1729):

Are you saying that x,y, and i are all variables? If I were to guess, it seems like the problem is asking when to complex (or imaginary) numbers are equal. If x,y, and i are all variables, then there is no way to solve exactly because you have one equation with three unknowns.

OpenStudy (anonymous):

It's about complex numbers

OpenStudy (anonymous):

@mathteacher1729

OpenStudy (mathteacher1729):

In that case you just match up the real component (the part not multiplied by i) and the imaginary component (the part being multiplied by i). Two complex numbers \[a + bi \text{ and } c + di \] are equal when \[a = c \text{ and } b = d\] Now look at \[-3 + yi \\ x + 6i\] What does x need to be and what does y need to be?

OpenStudy (anonymous):

x= -3 y= 6i ? @mathteacher1729

OpenStudy (mathteacher1729):

@lornbeach Yup, you got it! :)

OpenStudy (anonymous):

But they just cancel eachother out ! @mathteacher1729

OpenStudy (mathteacher1729):

You're thinking of solving an equation. You're not solving an equation here. You're just finding out what values make two complex numbers equal to each other. There is no arithmetic or algebra or anything else going on in this problem.

OpenStudy (anonymous):

Ohh thank you ((:

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