Question

find the following products using appropriate identities :(x-3)(x+5)

Answer 1

(x-3)(x+5)

= (x)^2 + (-3 + 5)x + (-3)(5)

= x^2 +2x - 15

Using identity [ (x +a) (x + b) = x^2 +(a+b)x + ab]

Answer 2

Given,

(x-3)(x+5)

To find,

The product of (x-3)(x+5) using an appropriate identity.

Solution,

The product of (x-3)(x+5) using an appropriate identity will be x² + 2x - 15.

We can easily solve this problem by following the given steps.

If we carefully observe the given expression then we find that the identity, (x+a)(x+b), is appropriate to solve it.

(x+a) (x+b) = x² + (a+b)x + ab

In this case, we have x = x, a = -3 and b = 5.

(x-3)(x+5) = (x)² + (-3+5)x + (-3×5)

(x-3)(x+5) = x² +2x -15

( Note that the two numbers with opposite signs are subtracted but the result is written with the sign of the greater number. And we multiply a positive and a negative integer, the answer will be negative.)

Hence, the product of (x-3)(x+5) using an appropriate identity is x² + 2x - 15.