(০.৯)৩+(০.৪)৩০.৯ +০.৪ এর মান কত?
ক
০.৩৬
খ
০.৫১
গ
০.৮১
ঘ
০.৬১
সঠিক উত্তর: ০.৬১
\frac{{{{\left( {0.9} \right)}^3} + {{\left( {0.4} \right)}^3}}}{{0.9 + 0.4}} = \frac{{\left( {0.9 + 0.4} \right)\left\{ {{{\left( {0.9} \right)}^2} - 0.9 \times 0.4 + {{\left( {0.4} \right)}^2}} \right\}}}{{\left( {0.9 + 0.4} \right)}} = \left\{ {{{\left( {0.9} \right)}^2} - 0.9 \times 0.4 + {{\left( {0.4} \right)}^2}} \right\} = 0.81 - 0.36 + 0.16 = 0.61