Q. Express as a complex number in simplest a+bi form:−4−6i16−28iAnswer:
Identify complex conjugate: Identify the complex conjugate of the denominator.To divide complex numbers, we multiply the numerator and the denominator by the complex conjugate of the denominator. The complex conjugate of (−4−6i) is (−4+6i).
Multiply by conjugate: Multiply the numerator and the denominator by the complex conjugate of the denominator.We have (16−28i)/(−4−6i). Multiply by (−4+6i)/(−4+6i) to get rid of the imaginary part in the denominator.
Distribute and multiply numerators: Apply the distributive property to multiply out the numerators.Multiply (16−28i) by (−4+6i).(16−28i)(−4+6i)=16(−4)+16(6i)−28i(−4)−28i(6i)
Calculate products in numerators: Calculate the products in the numerators.16(−4)=−6416(6i)=96i−28i(−4)=112i−28i(6i)=−168i2 (Remember that i2=−1)
Combine like terms in numerator: Combine like terms in the numerator.−64+96i+112i−168(−1)−64+208i+168104+208i
Distribute and multiply denominators: Apply the distributive property to multiply out the denominators.Multiply (−4−6i) by (−4+6i).(−4−6i)(−4+6i)=(−4)(−4)+(−4)(6i)−6i(−4)−6i(6i)
Calculate products in denominators: Calculate the products in the denominators.(−4)(−4)=16(−4)(6i)=−24i−6i(−4)=24i−6i(6i)=−36i2 (Again, i2=−1)
Combine like terms in denominator: Combine like terms in the denominator.16−24i+24i−36(−1)16+3652
Write in a+bi form: Write the complex number in a+bi form. Now we have the numerator 104+208i and the denominator 52. Divide both the real part and the imaginary part of the numerator by the denominator. (104+208i)/52104/52+(208i/52)2+4i
More problems from Write a quadratic function from its zeros