Question

Find the value of:

(i) (82)² – (18)² 

(ii) (128)² – (72)² 

(iii) 197 × 203

(iv) 198 x 198 - 102 x 102/96

Answer 1

(i) Given, 

(82)² – (18)² 

By using (a – b)(a + b) = a² – b² 

= (82 – 18)(82 + 18) 

= (64)(100) 

= 6400

(ii) (128)² – (72)² 

By using (a – b)(a + b) = a² – b² 

= (128 – 72)(128 + 72) 

= (56)(200) 

=11200

(iii) 197 × 203 

By converting the given number into the form of formula we get, 

= (200 – 3)(200 + 3) 

= (200)² –(3)² 

= 40000 – 9 = 39991

(iv) Given,

By using the formula (a – b)(a + b) = a² – b²

We get;