Question 104

What is the value of $$\frac{(0.7)^{3}-(0.4)^{3}}{(0.7)^{2}+\ 0.7\times0.4+(0.4)^{2}}\ $$?

Solution

Expression = $$\frac{(0.7)^{3}-(0.4)^{3}}{(0.7)^{2}+\ 0.7\times0.4+(0.4)^{2}}\ $$

Let $$x=0.7$$ and $$y=0.4$$

= $$\frac{x^3-y^3}{x^2+xy+y^2}$$

= $$\frac{(x-y)(x^2+xy+y^2)}{x^2+xy+y^2}$$

= $$x-y=0.7-0.4=0.3$$

=> Ans - (A)

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