( a x a x 4 ) + ( a x a x 6 ) = 250
a x a x 10 = 250
a x a = 250 : 10
a x a = 25
=> a = 5 .
\(\left(a\times a\times4\right)+\left(a\times a\times6\right)=250\)
\(4a^2+6a^2=250\)
\(10a^2=250\)
\(a^2=250:10\)
\(a^2=25\)
\(\Rightarrow\orbr{\begin{cases}a=5\\a=-5\end{cases}}\)
\(\left(a\times a\times4\right)+\left(a\times a\times6\right)=250\)
\(a\times a\times\left(4+6\right)=250\)
\(a\times a\times10=250\)
\(a\times a=25\)
\(\Rightarrow a=5\)hoặc \(a=-5\)