which expression is the factorization of $x^{2}+10x + 21$?\n$(x + 3)(x + 7)$\n$(x + 4)(x + 6)$\n$(x + 6)(x +…
which expression is the factorization of $x^{2}+10x + 21$?\n$(x + 3)(x + 7)$\n$(x + 4)(x + 6)$\n$(x + 6)(x + 15)$\n$(x + 7)(x + 14)$
Answer
Explanation:
Step1: Recall factoring quadratic form
For a quadratic $ax^{2}+bx + c$ (here $a = 1$, $b=10$, $c = 21$), we need two numbers that multiply to $ac=21$ and add up to $b = 10$.
Step2: Find the two - numbers
The numbers 3 and 7 multiply to $3\times7=21$ and add up to $3 + 7=10$.
Step3: Write the factored form
The factored form of $x^{2}+10x + 21$ is $(x + 3)(x+7)$.
Answer:
A. $(x + 3)(x + 7)$