CBSE Notes, Lectures

CBSE - Mathematics - Polynomials

Polynomials

NCERT Exercise Exercise 2.5

What are the possible expressions for the dimensions of the cuboids whose volumes are given below? (i) Volume : 3x2 - 12(ii) Volume : 12ky2 + 8ky - 20k

What are the possible expressions for the dimensions of the cuboids whose volumes are given below? (i) Volume : 3x2 - 12x
(ii) Volume : 12ky2 + 8ky - 20k

Answer

(i) Volume : 3x2 - 12
Since, volume is product of length, breadth and height therefore by factorizing the given volume, we can know the length, breadth and height of the cuboid. 
3x2 - 12x
= 3x(x - 4)
Possible expression for length = 3
Possible expression for breadth x
Possible expression for height (x - 4)

(ii) Volume : 12ky2 + 8ky - 20k 
Since, volume is product of length, breadth and height therefore by factorizing the given volume, we can know the length, breadth and height of the cuboid. 
12ky2 + 8ky - 20k
= 4k(3y2 + 2y - 5)
= 4k(3y2 +5y - 3y - 5)
4k[y(3y +5) - 1(3y + 5)]
4k (3y +5) (y - 1)
Possible expression for length = 4k
Possible expression for breadth (3y +5)
Possible expression for height (y - 1)

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