Q10 of 59 Page 38

Find the product:

(x – 3)(x + 3)(x2 + 9)

First solving (x – 3)(x + 3)

Using the identity (a +b) (a–b) = a2 – b2


Here a = x and b = 3


= x2 –32


= x2 – 9


Now (x2 – 9) (x2 + 9)


Again, using the identity (a +b) (a–b) = a2 – b2


Here a = x2 and b = 9


= (x2)2 – 92


= x4 –81 ( ∵ (ax)m = axm)


More from this chapter

All 59 →
8

Use the identity (a + b)(a – b) = a2 – b2 to find the products:

(i) (x – 6) (x + 6)


(ii) (3x + 5)(3x + 5)


(iii) (2a + 4b)(2a – 4b)


(iv)

9

Evaluate these using identity:

(i) 55 × 45 (ii) 33 × 27


(iii) 8.5 × 9.5 (iv) 102 × 98

 10

Find the product:

(2a + 3)(2a – 3)(4a2 + 9)

 10

Find the product:

(p + 2) (p – 2)(p2 + 4)