3. Factorise the following quadratic polynomials
by splitting the middle term :
(6) 6x2 + 7x - 20
(7) 15x2 + 7x - 2
(8) x2 - 4x - 77
(10) 12x2 + 23x + 5
(9) x2 + 2x - 143
Answers
Answer:
6. ( 2 x + 5 ) ( 3 x - 4 )
7. ( 3 x + 2 ) ( 5 x - 1 )
8. ( x - 11 ) ( x + 7 )
10. ( 3 x + 5 ) ( 4 x + 1 )
9. ( x + 13 ) ( x - 11 )
Step-by-step explanation:
6.
6 x² + 7 x - 20
= > 6 x² + 15 x - 8 x - 20
= > 3 x ( 2 x + 5 ) - 4 ( 2 x + 5 )
= > ( 2 x + 5 ) ( 3 x - 4 )
7.
15 x² + 7 x - 2
= > 15 x ² + 10 x - 3 x - 2
= > 5 x ( 3 x + 2 ) - ( 3 x + 2 )
= > ( 3 x + 2 ) ( 5 x - 1 )
8.
x² - 4 x - 77
= > x² - 11 x + 7 x - 77
= > x ( x - 11 ) + 7 ( x - 11 )
= > ( x - 11 ) ( x + 7 )
10.
12 x² + 23 x + 5
= > 12 x² + 20 x + 3 x + 5
= > 4 x ( 3 x + 5 ) + ( 3 x + 5 )
= > ( 3 x + 5 ) ( 4 x + 1 )
9.
x² + 2 x - 143
= > x² + 13 x - 11 x - 143
= > x ( x + 13 ) - 11 ( x + 13 )
= > ( x + 13 ) ( x - 11 )
Hence we get all required answer!
Answer:
i) 6. ( 2 x + 5 ) ( 3 x - 4 )
7. ( 3 x + 2 ) ( 5 x - 1 )
8. ( x - 11 ) ( x + 7 )
10. ( 3 x + 5 ) ( 4 x + 1 )
9. ( x + 13 ) ( x - 11 )
Step-by-step explanation:
6.
6 x² + 7 x - 20
= > 6 x² + 15 x - 8 x - 20
= > 3 x ( 2 x + 5 ) - 4 ( 2 x + 5 )
= > ( 2 x + 5 ) ( 3 x - 4 )
7.
15 x² + 7 x - 2
= > 15 x ² + 10 x - 3 x - 2
= > 5 x ( 3 x + 2 ) - ( 3 x + 2 )
= > ( 3 x + 2 ) ( 5 x - 1 )
8.
x² - 4 x - 77
= > x² - 11 x + 7 x - 77
= > x ( x - 11 ) + 7 ( x - 11 )
= > ( x - 11 ) ( x + 7 )
10.
12 x² + 23 x + 5
= > 12 x² + 20 x + 3 x + 5
= > 4 x ( 3 x + 5 ) + ( 3 x + 5 )
= > ( 3 x + 5 ) ( 4 x + 1 )
9.
x² + 2 x - 143
= > x² + 13 x - 11 x - 143
= > x ( x + 13 ) - 11 ( x + 13 )
= > ( x + 13 ) ( x - 11 )
Hence we get all required answer!