Final answer:
To factorise 15x³ + 3x²y fully, we identify the greatest common factor, which is 3x², and rewrite the expression as 3x²(5x + y).
Step-by-step explanation:
The question asks to factorise fully the expression 15x³ + 3x²y. The first step is to identify the greatest common factor (GCF) of the two terms. We can see that both terms have a factor of 3x². When we factor out 3x² from both terms, we are left with 5x and y as the other factors. Thus, the expression can be rewritten as:
3x²(5x + y)
This is the fully factorised form of the given expression, where 3x² is the GCF and (5x + y) is the remaining binomial factor.