Question 56

What is the value of $$[(0.7)^3 + (0.3)^3] \div [(0.7)^2- (0.7\times0.3) + (0.3)^2]?$$ ?

Solution

Expression : $$[(0.7)^3 + (0.3)^3] \div [(0.7)^2- (0.7\times0.3) + (0.3)^2]?$$

= $$\frac{(0.7)^3+(0.3)^3}{(0.7)^2-0.7\times0.3+(0.3)^2}$$

Let $$0.7=x$$ and $$0.3=y$$

$$\equiv\frac{(x)^3+(y)^3}{(x)^2-xy+(y)^2}$$

Using, $$(x^3+y^3)=(x+y)(x^2+y^2-xy)$$

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

= $$0.7+0.3=1$$

=> Ans - (C)

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