Q10 of 119 Page 45

Evaluate:

(i) 69 × 71 (ii) 94 × 106.

(i) We have

69 × 71 = (70 – 1) × (70 + 1)


= (702 – 12)


= 4900 – 1


= 4899


(ii) We have


94 × 106 = (100 – 6) × (100 + 6)


= (1002 – 62)


= 10000 – 36


= 9964


More from this chapter

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8

Using the formula (a + b)2 = (a2 + 2ab + b2), evaluate:

(i) (310)2 (ii) (508)2


(iii) (630)2

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Using the formula (a - b)2 = (a2 - 2ab + b2), evaluate:

(i) (196)2 (ii) (689)2 (iii) (891)2

 11

Evaluate:

(i) 88 × 92 (ii) 78 × 82.

 12

Fill in the blanks:

(i) The square of an even number is….


(ii) The square of an odd number is…….


(iii) The square of a proper fraction is ………..than the given fraction.


(iv) n2 = the sum of first n ……. natural numbers.