Question

(x-3) (x+5) with explanation please




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Answer 1

Answer:

(x-3)(x+5)

Apply identity..(x+a)(x+b)=x²+(a+b)x+ab

x²+(-3+5)x+3*5

x²+2x+15

Answer 2

Given

• (x - 3)(x + 5)

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To Do

• Simplify the expression

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Solution

First, we will observe the following question properly. We find that there are two methods to solve this question. The first method is directly simplifying and other is simplifying using identities.

Method 1 (Directly Simplifying)

⇒ (x - 3)(x + 5)

⇒ x (x + 5) - 3(x + 5)

⇒ x² + 5x - 3x - 15

⇒ x² + 2x - 15

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Method 2 (Using Identities)

⇒ (x - 3)(x + 5)

Identity we will use is → (x + a)(x + b) = x² + (a + b)x + ab

Here,

• x = x
• a = -3
• b = 5

⇒ (x - 3)(x + 5)

⇒ x² + (-3 + 5)x + -3(5)

⇒ x² + (2)x - 15

⇒ x² + 2x - 15

∴ (x - 3)(x + 5) = x² + 2x - 15

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