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secondary 2 | Maths
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Janelle
Janelle

secondary 2 chevron_right Maths chevron_right Singapore

hi i need help with this question thanks

Date Posted: 3 years ago
Views: 276
J
J
3 years ago
1225 ÷ 5 = 245
245 ÷ 5 = 49
49 ÷ 7 = 7

7 is prime.


So 1225 = 7 x 7 x 5 x 5 = 7² x 5²


if you want a perfect cube, the smallest we can go is :

7³ x 5³

= 7 x 5 x 7 x 5 x 7 x 5

= (7 x 5)³


Since 1225 = 7² x 5², we need to multiply by another 5 and another 7.

Smallest integer k

= 7 x 5

= 35

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Kaeden wong
Kaeden Wong's answer
10 answers (Tutor Details)
1st
Try to divide 1225 by 2 then 3 then 4. You would not be able to get a whole number but when divided by 5, you get 245. Continue dividing by the smallest integer that gives you a whole number. Since1225k needs to be a perfect cube, there needs to be 3 of each number so there are 2 5s and 2 7s. So k=7x5