Linear Equations
A linear equation has the form ax + b = c, where a, b, and c are constants and x is the unknown.
The solution process involves isolating x by performing inverse operations on both sides.
Special cases: if a = 0 and b = c, there are infinitely many solutions. If a = 0 and b is not equal to c, there is no solution.
Quadratic Equations
A quadratic equation has the form ax^2 + bx + c = 0. The quadratic formula provides a direct method to find solutions:
x = (-b +/- sqrt(b^2 - 4ac)) / (2a)
The discriminant (b^2 - 4ac) determines root nature:
- Positive: Two distinct real roots
- Zero: One repeated real root
- Negative: Two complex conjugate roots
Systems of Equations
A system of two linear equations with two unknowns can be solved using elimination or Cramer's rule.
The elimination method involves manipulating equations to eliminate one variable, solving for the other,
then substituting back.
Systems may have one unique solution (intersecting lines), no solution (parallel lines),
or infinitely many solutions (same line).
Solution Verification
After finding the solution, substitute the value(s) back into the original equation.
If both sides evaluate to the same number, the solution is verified. This is an essential step in algebra
to confirm accuracy.