Solve (x+9)(x-9)

$$(x+9)(x-9)$$

Evaluate

$$x^{2}-81$$

Solution Steps

Multiplication can be transformed into difference of squares using the rule: \left(a-b\right)\left(a+b\right)=a^{2}-b^{2}.

$$x^{2}-9^{2}$$

Calculate 9 to the power of 2 and get 81.

$$x^{2}-81$$

Expand

$$x^{2}-81$$

Solution Steps

Multiplication can be transformed into difference of squares using the rule: \left(a-b\right)\left(a+b\right)=a^{2}-b^{2}.

$$x^{2}-9^{2}$$

Calculate 9 to the power of 2 and get 81.

$$x^{2}-81$$