Factorise each of the following:
(i) 27y 3 + 125z 3
(ii) 64m3 – 343n 3
[ Hint : See Question 9. ]
(i) 27 y3 + 125 z3
= (3y)3 + (5z)3
= (3y + 5z) [(3y)2 + (5z)2 - (3y)(5z) ] [∵ a3 + b3 ]
= (a + b) (a2 + b2 - ab)
= (3y + 5z) [9y2 + 25z2 - 15yz]
(ii) 64m3 - 343n3
= (4m)3 - (7n)3
= (4m - 7n)[ (4m)2 + (7n)2 + (4m) (7n) ] [∵ a3 - b3 = (a - b) (a2 + b2 + 2ab) ]
= (4m - 7n) [16m2 + 49n2 + 28mn ]
Length (in hours) | Number of lamps |
|---|---|
300 − 400 | 14 |
400 − 500 | 56 |
500 − 600 | 60 |
600 − 700 | 86 |
700 − 800 | 74 |
800 − 900 | 62 |
900 − 1000 | 48 |
(i) Represent the given information with the help of a histogram.
(ii) How many lamps have a lifetime of more than 700 hours?
Why was Santosh sent to the local school?