Question

Simplify $(x+3)(x+5)$.

• A. $x^2+6x+9$
• B. $x^2+8x+15$
• C. $x^2+9x+6$
• D. $9x^2+6x+9$

Answer 1

The correct option is B

$x^2+8x+15$

To simplify: $(x+3)(x+5)$

Using the identity $\left[\right(x+a\left)\right(x+b{)}^2=x^2+(a+b)x+ab]$
we get,

$(x+3)(x+5)=x^2+(3+5)x+3\times 5=x^2+8x+15$