Using prime factorisatioji,

Question:

 Using prime factorisatioji, find which of the following are perfect cubes,

(a) 128

(b) 343

(c) 729

(d) 1331

Solution:

(a) We have, 128 = 2 x 2 x 2 x 2 x 2 x 2 x 2

Since, 2 remains after grouping in triplets.

So, 128 is not a perfect cube.

(b) We have, 343 = 7 x 7 x 7

Since, the prime factors appear in triplets.

So, 343 is a perfect cube.

(c) We have, 729 = 3 x 3 x 3 x 3 x 3 x3

Since, the prime factors appear in triplets.

So, 729 is a perfect cube.

(d) We have, 1331 =11x11x11

Since, the prime factors appear in triplets.

So, 1331 is a perfect cube.

Leave a comment

Close
faculty

Click here to get exam-ready with eSaral

For making your preparation journey smoother of JEE, NEET and Class 8 to 10, grab our app now.

Download Now