2.
(vi)
(ii) 4y2 + 13y - 17
(0) 1952 + 40kl – 5912
(viii) p2 + 6p - 16
Factorise the following expressions:
(i) 2r2 - 9r - 45
(iv) 8r2 - 48rs + 70s2
(vii) 3x2 - 4x - 4
(ix) x2 = 17x - 60 [NCERT Exemplar]
3. Simplify the following expressions:
x2 – 21x +90
7x2 - 19x - 6
(i)
(ii)
(x - 15)
7x+2
5y2 – 40yz-10022
4x2 – 11x +7
(iv)
y-102
X-1
4. The curved surface area of a cylinder is 21 (y2 – 7y +12) and i
cylinder.
Answers
Answer:
(i) a 2 + 8 a + 16
Answer:
This equation can be facorised by using the identity;
( a + b ) 2 = a 2 + 2 a b + b 2
Factors = ( a + 4 ) 2 = ( a + 4 ) ( a + 4 )
(ii) p 2 – 10 p + 25
Answer:
This equation can be factorised by using the identity;
( a – b ) 2 = a 2 – 2 a b + b 2
Factors = ( p – 5 ) 2
(iii) 25 m 2 + 30 m + 9
Answer:
= ( 5 m – 3 ) 2
(iv) 49 y 2 + 84 y z + 36 z 2
Answer:
( 7 y+ 6 z ) 2
(v) 4 x 2 – 8 x + 4
Answer:
( 2 x – 2 ) 2 (vi) 121 b 2 – 88 b c + 16 c 2
Answer:
( 11 b – 4 c ) 2
(vii) ( l + m ) 2 – 4 l m
Answer:
l 2 + m 2 + 2 l m − 4 l m
l 2 + m 2 − 2 l m
= ( l + m ) 2
(viii) a 4 + 2 a 2 b 2 + b 4
Answer: This can be solved using
( a + b ) 2
= a 2 + 2 a b + b 2
Hence,
a 4 + 2 a 2 b 2 + b 4
= ( a 2 + b 2 ) 2