Explicație pas cu pas:
1.
[tex]3xy(x + y) = 3 \times ( - 7) \times 2 = - 62[/tex]
2.
[tex] {x}^{2} \times {y}^{2} \times (x + y) = 24 \\ {x}^{2} {y}^{2} 6 = 24 \\ {x}^{2} {y}^{2} = 24 \div 6 \\ {(xy)}^{2} = 4 \\ {(xy)}^{2} = {2}^{2} \\ xy = 2[/tex]
3a.
[tex]a = {x}^{2} + x - 2x - 2 = {x}^{2} - x - 2[/tex]
[tex]b = {x}^{2} + 3x - 2x - 6 = {x}^{2} + x - 6[/tex]
[tex]b - a = {x}^{2} + x - 6 - {x}^{2} + x + 2 = 2x - 4[/tex]
b.
[tex](x + 1)(x - 2) = 3 \\ {x}^{2} - x - 2 = 3 \\ {x }^{2} - x = 5 \\ x(x - 1) = 5\\ (x - 2)(x + 3) = 6 \\ {x}^{2} + x - 6 = 6 \\ {x }^{2} + x = 12 \\ x(x + 1) = 12 \\ x = 3[/tex]
