Question

Factor: 5x2 – 15x – 20.

(a) 5(x-4)(x+1),

(b) -2(x-4)(x+5),

(c) -5(x+4)(x-1),

(d) 5(x+4)(x+1).

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Answer 1

Answer:-

5x2 – 15x – 20

= 5 (x2 – 3x – 4)

= 5 (x2 – 4x + x – 4)

= 5 (x(x - 4) +1(x - 4)

= 5 (x-4)(x+1)

Answer is Option A

• Factor is also know as factorisation
• Factorisation means writing a question or answer or a reply.

Explanations in Hindi :-

• फैक्टर को कारक के रूप में भी जाना जाता है
• फैक्टराइजेशन का अर्थ है प्रश्न या उत्तर लिखना

Answer 2

Hi there !!

5x²-15x-20

Taking 5 as common.

5(x²-3x-4)

5(x² - 3x- 4 )

5(x² - 4x + x-4) [Splitting the middle term by setting up product and sum of that constant term]

5( x( x-4)+1(x-4))

5(x-4)+(x+1)

Option A will answer

We can do this question by various methods like :

• Quadratic formula
• Completing the square
• Factorisation (Middle term Splitting)

Thankyou :)