Explicación paso a paso:
[tex]13x + 21x = 34x[/tex]
[tex]13 {x}^{2} - 15 {x}^{2} = - 2 {x}^{2} [/tex]
[tex]2ab \: - 6ab = - 4ab[/tex]
[tex]3xy \: + 2 xy \: = 5xy[/tex]
[tex]5x(3 {x}^{2} ) = 15 {x}^{3} [/tex]
[tex]2x(4x) = 8 {x}^{2} [/tex]
[tex]15 {a}^{9} \div 5 {a}^{7} = 3 {a}^{2} [/tex]
[tex]100 {b}^{6} \div 20 {b}^{6} = 5[/tex]
[tex]2ab(5 {ab}^{2} ) = 10 {ab}^{3} [/tex]
[tex]( - 2 {x}^{3} ) ^{2} = - 2 {x}^{6} [/tex]
