BeginnerTopic 8 of 104Engineering Mathematics
Quadratic equations
ax^2+bx+c=0 is solved by x=(-b±√(b²-4ac))/2a; the discriminant tells how many real roots exist.
In depth
For ax²+bx+c=0 the roots are x=(-b±√(b²-4ac))/(2a). The discriminant b²-4ac decides: positive gives two real roots, zero gives one repeated root, negative gives a complex pair. Factoring and completing the square are alternative methods.
Key points
- Sum of roots = -b/a
- Product of roots = c/a
- The graph is a parabola
Examplex²-5x+6=0 factors to (x-2)(x-3), roots 2 and 3.
Quadratics appear in projectile range, energy balances and the roots of characteristic equations, so solving them quickly is a core skill.
What is Quadratic equations?
ax^2+bx+c=0 is solved by x=(-b±√(b²-4ac))/2a; the discriminant tells how many real roots exist.
Why is it important to understand quadratic equations?
Quadratics appear in projectile range, energy balances and the roots of characteristic equations, so solving them quickly is a core skill.
What does the discriminant b² minus 4ac tell me?
If it is positive there are two distinct real roots, zero gives one repeated root, and negative gives two complex roots, which often means oscillation.
Why does the formula have a plus-or-minus sign?
A quadratic usually has two solutions, one for each sign. The physical problem usually tells you which one is meaningful.
How is Quadratic equations used in practice?
Typical applications include finding the landing time of a projectile, solving for the natural frequency of a second-order circuit and sizing a rectangular section for a required area.
What should I learn before Quadratic equations?
Study "Linear equations" first (topic 7 of 104 in Engineering Mathematics). It covers the groundwork this topic builds on.
What are the key points of Quadratic equations?
Sum of roots = -b/a. Product of roots = c/a. The graph is a parabola.
Can you give an example of Quadratic equations?
x²-5x+6=0 factors to (x-2)(x-3), roots 2 and 3.
What comes after Quadratic equations?
The next topic is "Exponents and logarithms", which builds directly on this one.
How difficult is Quadratic equations?
It is classed as Beginner in Engineering Mathematics (topic 8 of 104). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.