01. Complex Numbers
Real and imaginary parts, conjugates, modulus, argument and complex arithmetic.
NUMBER SYSTEMSExplore complex numbers, matrices, vectors, advanced calculus, differential equations and mathematical proof through clear lessons and interactive practice.
Build advanced mathematical understanding one concept at a time.
Real and imaginary parts, conjugates, modulus, argument and complex arithmetic.
NUMBER SYSTEMSMatrix operations, determinants, inverses and solving simultaneous equations.
LINEAR ALGEBRAVector arithmetic, magnitude, direction, scalar products and geometric applications.
GEOMETRYIntegration techniques, definite integrals and applications to area.
CALCULUSRates of change, stationary points, product rules and chain rules.
CALCULUSArithmetic and geometric progressions, sums and convergence ideas.
SEQUENCESExpand powers, calculate coefficients and work with general binomial terms.
ALGEBRAUnderstand derivatives in equations and solve introductory differential equations.
MODELLINGConstruct logical arguments, direct proofs and proof by contradiction.
REASONINGApproximate roots, use iteration and understand numerical accuracy.
APPROXIMATIONUse identities, equations, radians and trigonometric relationships.
TRIGONOMETRYTranslate real situations into equations, state assumptions and interpret results.
APPLICATIONSRead the explanations and formulas before attempting the practice test.
A complex number has a real part and an imaginary part. The imaginary unit \(i\) satisfies \(i^2=-1\).
Example: if \(z=3+4i\), its real part is 3 and its imaginary part is 4.
For \(z=3+4i\), the modulus is \(\sqrt{3^2+4^2}=5\).
The conjugate of a complex number is formed by changing the sign of its imaginary part.
Example: the conjugate of \(2+3i\) is \(2-3i\).
A matrix is a rectangular arrangement of numbers. Addition requires matrices of the same dimensions.
For a 2 × 2 matrix, the determinant is the top-left entry times the bottom-right entry minus the other diagonal product.
The inverse exists only when the determinant is non-zero.
A vector has magnitude and direction. In two dimensions, its components can be written as \((a,b)\).
Example: the magnitude of \((3,4)\) is 5.
If the scalar product is zero, two non-zero vectors are perpendicular.
Differentiation measures the instantaneous rate of change of a function.
Example:
At a stationary point, the first derivative is zero, though the point may be a maximum, minimum or stationary point of inflection.
Integration reverses differentiation for many functions and can calculate accumulated quantities.
Example:
The constant \(C\) appears in indefinite integration because a constant disappears when differentiated.
An arithmetic progression has a constant difference between consecutive terms.
Here \(a\) is the first term and \(d\) is the common difference.
A geometric progression has a constant ratio between consecutive terms.
For an infinite geometric series, the sum exists when \(|r|<1\):
For a non-negative integer \(n\), the binomial theorem expands a power of a sum.
Example:
The coefficients come from binomial coefficients, which can be calculated using factorials.
A differential equation relates a function to one or more of its derivatives.
One general solution is:
The constant \(A\) is determined using an initial condition when one is given.
A proof is a logically complete argument showing that a statement follows from accepted facts or assumptions.
Direct proof: begin with known information and logically derive the result.
Contradiction: assume the statement is false and show that this leads to a contradiction.
Numerical methods can approximate solutions when exact algebraic solutions are difficult to obtain.
In fixed-point iteration, repeatedly apply the function \(g\) to the previous approximation.
Convergence depends on the function and starting value. Always consider the required accuracy and check whether the method converges.
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