RS Aggarwal Class 8 Math Seventh Chapter Factorisation Exercise 7C Solution

RS Aggarwal Class 8 Math Seventh Chapter Factorisation Exercise 7C Solution

EXERCISE 7C

Factorise:

FORMULA:

(i) a2 + 2ab + b2 = (a + b)2

(ii) a2 – 2ab + b2 = (a – b)2

(1) x2 + 8x + 16

= (x)2 + (2 × x × 4) + (4)2

= (x + 4)2

(2) x2 + 14x + 49

= (x)2 + (2 × x × 7) + (7)2

= (x + 7)2

(3) 1 + 2x + x2

= (1)2 + (2 × 1 × x) + (x)2

= (1 + x)2

(4) 9 + 6z + z2

= (3)2 + (2 × 3 × z) + (z)2

= (3 + z)2

(5) x2 + 6ax + 9a2

= (x)2 + (2 × x × 3a) + (3a)2

= (x + 3a)2

(6) 4y2 + 20y + 25

= (2y)2 + (2 × 2y × 5) + (5)2

= (2y + 5)2

(7) 36a2 + 36a + 9

= (6a)2 + (2 × 6a × 3) + (3)2

= (6a + 3)2

(8) 9m2 + 24m + 16

= (3m)2 + (2 × 3m × 4) + (4)2

= (3m + 4)2

(10) 49a2 + 84ab + 36b2

= (7a)2 + (2 × 7a + 6b) + (6b)2

= (7a + 6b)2

(11) p2 – 10p + 25

= (p)2 – (2 × p × 5) + (5)2

= (p – 5)2

(12) 121a2 – 88ab + 16b2

= (11a)2 – (2 × 11a × 4b) + (4b)2

= (11a – 4b)2

(13) 1 – 6x + 9x2

= (1)2 – (2 × 1 × 3x) + (3x)2

= (1 – 3x)2

(14) 9y2 – 12y + 4

= (3y)2 – (2 × 3y × 2) + (2)2

= (3y – 2)2

(15) 16x2 – 24x + 9

= (4x)2 – (2 × 4x × 3) + (3)2

= (4x – 3)2

(16) m2 – 4mn + 4n2

= (m)2 – (2 × m × 2n) + (2n)2

= (m – 2n)2

(17) a2b2 – 6abc + 9c2

= (ab)2 – (2 × ab × 3c) + (3c)2

= (ab – 3c)2

(18) m4 + 2m2n2 + n4

= (m2)2 + (2 × m2 × n2) + (n2)2

= (m2 + n2)2

(19) (l + m)2 – 4lm

= l2 + 2lm + m2 – 4lm

= l2 – 2lm + m2

= (l – m)2


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