Question

sabendo que a sequência (x+3, x2, 6x+1) é uma P.A., determine o valor de x.​

Answer 1

$> resolucao \\ \\ \geqslant progressao \: aritmetica \\ \\ a2 = \frac{a1 + a3}{2} \\ {x}^{2} = \frac{x + 3 + 6x + 1}{2} \\ 2 {x}^{2} = x + 3 + 6x + 1 \\ 2 {x}^{2} - 7x - 4 = 0 \\ \\ delta = ( - 7) {}^{2} + 4.2.( - 4) \\ delta = 49 + 32 \\ delta = 81 \\ delta = \sqrt{81} \\ delta = + - 9 \\ \\ x1 = \frac{7 + 9}{4} \\ x1 = \frac{16}{4} \\ x1 = 4 \\ \\ x2 = \frac{7 - 9}{4} \\ x2 = - \frac{2}{4} \\ x2 = - \frac{1}{2} \\ \\ \\ \geqslant \leqslant \geqslant \leqslant \geqslant \leqslant \geqslant \leqslant \geqslant$