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The value of (1.25)3 - 2.25 (1.25)2 + 3.75 (0.75)2 - (0.75)3 is :
Answer & Solution
Correct Answer:
Option
D
Given expression :
(1.25)3 - (0.75)3 - 3 × (1.25)2 × 0.75 + 3 × 1.25 × (0.75)2
= (1.25 - 0.75)3
= (0.5)3
= $${\left( {\frac{1}{2}} \right)^3}$$
= $$\frac{1}{8}$$
[∵ (a - b)3 = a3 - b3 - 3a2 b + 3ab2]
(1.25)3 - (0.75)3 - 3 × (1.25)2 × 0.75 + 3 × 1.25 × (0.75)2
= (1.25 - 0.75)3
= (0.5)3
= $${\left( {\frac{1}{2}} \right)^3}$$
= $$\frac{1}{8}$$
[∵ (a - b)3 = a3 - b3 - 3a2 b + 3ab2]
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