Q. Express as a complex number in simplest a+bi form:−7−3i9−2iAnswer:
Multiply by Conjugate: Multiply the numerator and denominator by the complex conjugate of the denominator to eliminate the imaginary part in the denominator.The complex conjugate of (−7−3i) is (−7+3i).−7−3i9−2i⋅−7+3i−7+3i
Apply Distributive Property: Apply the distributive property (foil method) to multiply out the numerators and the denominators.Numerator: (9−2i)(−7+3i)=9⋅(−7)+9⋅3i+(−2i)⋅(−7)+(−2i)⋅3iDenominator: (−7−3i)(−7+3i)=(−7)⋅(−7)+(−7)⋅3i+(−3i)⋅(−7)−3i⋅3i
Perform Multiplication: Perform the multiplication.Numerator: −63+27i−14i−6i2Denominator: 49−21i+21i−9i2Since i2=−1, replace i2 with −1 in both the numerator and the denominator.
Simplify Using i2: Simplify the expressions by combining like terms and using i2=−1.Numerator: −63+27i−14i+6(−1)=−63+13i−6=−69+13iDenominator: 49−21i+21i+9(−1)=49+9=58
Divide Numerator by Denominator: Divide the simplified numerator by the simplified denominator.(−69+13i)/58Separate the real and imaginary parts and divide each by 58.Real part: −69/58Imaginary part: 13i/58