Question

1) 4 x elevado a 2 + 12x = 0

2) 22 x + 11 x = 0

3) x elevado a 2 - 42 x = 0

4) 8 x elevado a 2 + 72 = 0

5) 8 x elevado a 2 - 200 = 0

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Answer 1

Resposta:

$1) \: \: \: {4x}^{2} + 12x = 0 \\ x \times (4x + 12) = 0 \\ 4x + 12 = 0 \\ 4x = - 12 \\ x = - \frac{12}{4} \\ x = - 3 \\ \\ 2) \: \: \: 22x + 11x = 0 \\ 33x = 0 \\ x = \frac{0}{33} \\ x = 0 \\ \\ 3) \: \: \: {x}^{2} - 42x = 0 \\ x \times (x - 42) = 0 \\ x - 42 = 0 \\ x = 42 \\ \\ 4) \: \: \: {8x}^{2} + 72 = 0 \\ {8x}^{2} = - 72 \\ {x}^{2} = - \frac{72}{8} \\ {x}^{2} = - 9 \\ x = \sqrt{ - 9} \\ \\ 5) \: \: \: {8x}^{2} - 200 = 0 \\ {8x}^{2} = 200 \\ {x}^{2} = \frac{200}{8} \\ {x}^{2} = \frac{200 \div 4}{8 \div 4} \\ {x}^{2} = \frac{50}{2} \\ {x}^{2} = 25 \\ x = \sqrt{25 } \\ x = 5$