Q. Simplify the expression to a + bi form:(12−4i)(−6−9i)Answer:
Use Distributive Property: To simplify the expression (12−4i)(−6−9i), we need to use the distributive property (also known as the FOIL method for binomials), which states that for any complex numbers a, b, c, and d, (a+bi)(c+di)=ac+adi+bci+bdi2. Let's multiply the real parts and the imaginary parts accordingly.
Multiply Real Parts: First, we multiply the real parts: 12×(−6)=−72.
Multiply Real and Imaginary: Next, we multiply the real part of the first complex number by the imaginary part of the second complex number: 12×(−9i)=−108i.
Multiply Imaginary and Real: Then, we multiply the imaginary part of the first complex number by the real part of the second complex number: (−4i)×(−6)=24i.
Multiply Imaginary Parts: Finally, we multiply the imaginary parts: (−4i)×(−9i). Since i2=−1, this becomes −4×−9×i2=36×−1=−36.
Combine All Parts: Now, we combine all the parts: real part −72, imaginary parts −108i+24i, and the result of the multiplication of the imaginary parts −36.So, −72−108i+24i−36.
Combine Like Terms: Combine like terms: −72−36 is the real part, and −108i+24i is the imaginary part.The real part is −72−36=−108.The imaginary part is −108i+24i=−84i.
Get Final Expression: Putting it all together, we get the expression in a+bi form: −108−84i.
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