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The easiest way to do this is treat i like a variable and multiply the binomials and combine like powers of i, then anywhere there is i², substitute it with (-1).
So (4 + 3x)(3 - 4x) = {using FOIL} 4*3 - 4*4*x + 3*3*x - 3*4*x² = 12 -7x - 12x²
So with x = i, you have 12 - 7i - 12*(i²) = 12 - 7i - -12 = 24 - 7i
One quick check to see if there is an error: The magnitude of the product of the two complex binomials will equal the product of the magnitude of each factor.
Magnitude of a + bi = sqrt(a² + b²). The magnitudes of two numbers that are multiplied are: sqrt(4² + 3²) = 5, and sqrt(3² + (-4)²) = 5. The magnitude of the answer is sqrt(24² + (-7)²) = sqrt(576 + 49) = sqrt(625) = 25, which is 5 times 5.
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What is the product of these complex numbers (3-4i)(1-i)?
(3-4i)(1-i) = (3x1) + (3 x -i) + (-4i x 1) + ( -4i x -i) = 3 - 3i -4i -4 = -1 - 7i
What is conjugate of 4i open bracket -2 -3i close bracket?
4i(-2 -3i) = 4i×-2 - 4i×-3i = -8i -12i² = -8i + 12 = 12 -8i → the conjugate is 12 + 8i
Plot the number in a complex plane -1-3i?
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Find the absolute value of the complex number z equals 3 plus 4i?
('|x|' = Absolute value of x) |3+4i| = √(32 + 42) = √(9+16) = √25 = 5 Thus |3+4i| = 5.
When the sum of the complex numbers 3 plus 2I and 6 - 4I is graphed in which quadrant does it lie?
3+2i + 6-4i = 9-2i The real part of this number is positive, therefore it lies in Q1 or Q4. The imaginary part is negative, therefore it is in Q3 or Q4. Q4 is the common possibility, therefore 9-2i is in Q4.
