<span>2<span>a^3</span>+<span>a^2</span>−1−3<span>a^2</span>+<span>a^3</span>−a=</span><span>3<span>a^3</span>−2<span>a^2</span>−1−a=</span><span><span>3<span>a^3</span>−2<span>a^2</span>−a−1</span></span>
1) x=5y+2
2(5y+2)-y=7
10y+4-y=7
9y=3
y=1/3 ===> x= 5*1/3=5/3