S3 · Algebra · ALG.EQ.QUADRATIC

Solve quadratic equations

Solve quadratic equations

Practice this skill
Intuition

Understand first, compress later.

Algebra describes structures generally: a symbol stands for a number, while the rules remain the same.

Switch representations
Linear functionf(x) = x
-8-6-4-202468-10-5510xy
Δx = 2Δy = 2
y-intercept
graph of fΔx (run)Δy (rise)y-intercept
The line meets the y-axis at 0. From there 2 to the right and 2 up: that ratio is the slope m = 1.
Formal view

You can solve quadratic equations when you can recognise the underlying objects, select valid rules and check each step for equivalence or logical implication.

Why does it work?

This skill sits on a prerequisite network. If a step is unstable, repair the missing prerequisite instead of merely doing more items of the same type.