[tex]4. 3x + 12 = 33 - 5.7x \\ 4.3x + 5.7x = 33 - 12 \\ 10x = 21 \\ x = \frac{21}{10} [/tex]
[tex] \frac{4 + 3x}{5} = \frac{7x - 1}{8} \\ 8(4 + 3x) = 5(7x - 1) \\ 32 + 24x = 35x - 5 \\ 24x - 35x = - 5 - 32 \\ \ - 11x = - 37 \\ x = \frac{ - 37}{ - 11} = \frac{37}{11} [/tex]
[tex](3x + 7)(4x - 8) = 0 \\3x + 7 = 0 \\ 3x = - 7 \\ x = \frac{ - 7}{3} \\ 4x - 8 = 0 \\ 4x = 8 \\ x = \frac{8}{4} = 2[/tex]
[tex]8 + 2x {}^{2} = 40 \\ 2x { }^{2} = 40 - 8 \\ 2 {x}^{2} = 32 \\ x {}^{2} = \frac{32}{2} = 16 \\ x = + \sqrt{16} \: \: ou \: x = - \sqrt{16 } \\ x = + 4 \: \: \: \: \: \: \: \: x = - 4[/tex]
[tex] \frac{7x}{ 3} - 2 = \frac{5x}{6} + 1 \\ \frac{7x - 6}{3} = \frac{5x + 6}{6} \\ 6(7x - 6) = 3(5x + 6) \\ 42x - 36 = 15x + 18 \\ 42x - 15x = 18 + 36 \\ 27x = 54 \\ x = \frac{54}{27} = 2[/tex]
[tex](9x - 4)( - 2 + 5x) - (9x - 4)(3x - 5) = 0 \\ (9 x - 4)(( - 2 + 5x) - (3x - 5)) = 0 \\ (9x - 4)( - 2 + 5x - 3x + 5) = 0 \\ (9x - 4)(2x + 3) = 0 \\ 9x - 4 = 0 \\ 9x = 4 \\ x = \frac{4}{9} \\ 2x + 3 = 0 \\ 2x = - 3 \\ x = \frac{ - 3}{2} [/tex]
[tex]9x {}^{2} - 36 = 0 \\ 9(x {}^{2} - 4) = 0 \\ {x}^{2} - 4 = 0 \\ {x}^{2} = 4 \\ x = + \sqrt{4 \: } ou - \sqrt{4} \\ x = +2 \: ou - 2[/tex]
