Question

what would be the product of ((x + 2.5)(x - 2.5))?
a. (x^2 + 5)
b. (x^2 - 5)
c. (x^2 + 6.25)
d. (x^2 - 6.25)

Explanation:

Step1: Apply difference of squares

Recall $(a+b)(a-b)=a^2-b^2$
Here $a=x$, $b=2.5$

Step2: Calculate $a^2$ and $b^2$

$a^2 = x^2$, $b^2 = 2.5^2 = 6.25$

Step3: Substitute into formula

$(x+2.5)(x-2.5)=x^2 - 6.25$

Answer:

d. $x^2 - 6.25$