(Math Quiz 10 – CT) In the expansion ({left( {{rm{0,2; + ;0,8}}} right)^{rm{5}}}), the fourth term is:

• Question:

In the expansion $${\left( {{\rm{0.2\; + \;0,8}}} \right)^{\rm{5}}}$$, the fourth term is:

Reference explanation:

The general term in the above expansion is

$${T_{k + 1}} = C_5^k. {\left( {0,2} \right)^{5 – k}}. {\left( {0,8} \right)^k}$$

So the fourth term is

$${T_4} = C_5^3. {\left( {0,2} \right)^2}. {\left( {0.8} \right)^3} = 0.2028$$.