factor. $2x^2 + 21x + 10$

factor.
$2x^2 + 21x + 10$

We need two numbers that multiply to $2\times10 = 20$ and add up to $21$. The numbers are $20$ and $1$ since $20\times1 = 20$ and $20 + 1=21$.

Rewrite $21x$ as $20x+x$ in the quadratic expression: $2x^{2}+20x + x+10$.

Group the first two terms and the last two terms: $(2x^{2}+20x)+(x + 10)$.

Factor out $2x$ from the first group and $1$ from the second group: $2x(x + 10)+1(x + 10)$.

Factor out $(x + 10)$ from both terms: $(2x + 1)(x + 10)$.

$(2x + 1)(x + 10)$