JAMB 2015 · UTME · Q3

Multiply $(x + 3y + 5)$ by $(2x^2 + 5y + 2)$ .

Worked solution (try it first)

Multiply each term of $x + 3y + 5$ by the second bracket: $x$ gives $2x^3 + 5xy + 2x$ , and $3y$ gives $6x^2y + 15y^2 + 6y$ .
$5$ gives $10x^2 + 25y + 10$ .
Collect like terms: the only ones to combine are $6y + 25y = 31y$ .
So the product is $2x^3 + 6yx^2 + 5xy + 15y^2 + 31y + 10x^2 + 2x + 10$ , option B.