Mathematics Grade 11 15 min

Balance equations - four or more digits

Balance equations - four or more digits

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1

Introduction & Learning Objectives

Learning Objectives Identify the real and imaginary parts of a complex equation involving large numbers. Solve for an unknown complex variable by equating the real and imaginary components of an equation. Apply the complex conjugate to simplify and solve equations requiring division of complex numbers with four or more digits. Perform multiplication and division operations on complex numbers that have large numerical coefficients. Set up and solve a system of two linear equations derived from a single complex equation. Verify the solution to a complex equation by substituting the result back into the original equation. How can engineers balance the voltage in a city's power grid, where values are in the thousands, using imaginary numbers? ⚡️Let's find out! This t...
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Key Concepts & Vocabulary

TermDefinitionExample Complex EquationAn equation that contains at least one complex number. To 'balance' it means to find the value(s) of the variable(s) that make the equation true.(2000 + 3000i) * z = 10000 - 5000i Equality of Complex NumbersTwo complex numbers are equal if and only if their real parts are equal and their imaginary parts are equal.If x + yi = 4500 - 1200i, then x must be 4500 and y must be -1200. Complex VariableA variable that represents a complex number, typically written in the form z = x + yi, where x and y are unknown real numbers.In the equation (1500i)z = 3000, z is the complex variable. Complex ConjugateThe complex conjugate of a complex number a + bi is a - bi. It is denoted by a bar over the number. Multiplying a complex number by its conjugate resu...
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Core Formulas

Principle of Equality For two complex numbers z_1 = a + bi and z_2 = c + di, if z_1 = z_2, then a = c and b = d. This is the most fundamental rule for balancing complex equations. It allows you to break one complex equation into two separate, real-valued equations that are often easier to solve. Division using the Complex Conjugate \frac{a + bi}{c + di} = \frac{a + bi}{c + di} \cdot \frac{c - di}{c - di} = \frac{(ac + bd) + (bc - ad)i}{c^2 + d^2} To solve for a variable when it is being multiplied by a complex number, you must divide. This rule transforms the division problem into a multiplication problem by making the denominator a real number.

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Sample Practice Questions

Challenging
Solve for the complex number z = x + yi in the equation (1000 + 2000i)z = 18000i + (3000 - 4000i)z.
A.z = 2.7 - 0.9i
B.z = -2.7 + 0.9i
C.z = 1.8 + 3.6i
D.z = -1.8 - 3.6i
Challenging
Find the complex number z = x + yi that satisfies the equation 2000z + 3000z̄ = 25000 - 5000i, where z̄ is the complex conjugate of z.
A.z = 5 - 5i
B.z = 5 + 5i
C.z = 5000 + 5000i
D.z = 25 - 5i
Challenging
This question is based on the tutorial's Worked Example 2. Calculate the value of z = ( (8000 + 11000i) / (3000 - 4000i) ) * 1000.
A.z = -80 + 260i
B.z = 800 - 2600i
C.z = -800 + 2600i
D.z = 2600 - 800i

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