I am part of the way through a binomial expansion problem, and it isn't the problem itself that concerns me, what I am curious about is how the solution has factorised the equation.
At some point in the problem, I ended up with the equation
4a3−9a2+5=0 (Is this a cubic equation? I can see that it is raised to the power 3 but only has 3 terms, whereas a cubic usually has four terms. Should I be imagining the equation as
4a3−9a2+0a+5? Or is this not a cubic?)
Anyhow, the solution shows this equation factorised in a single step. I have attached a screenshot of this.
Now, I know I can obtain any factors of a cubic function using the factor theorem and algebraic division, but the solution has no mention of this and seems to split the equation into a quadratic and a linear factor instantly in a single step. This has made me curious to know if there is a technique I can apply to factorise equations such as this instantly, without having to go through the long-winded factor theorem followed by algebraic division. Is this possible, and is it something I am expected to do in the context of A-Level Maths?