3+7*(1+x)^2=(1+3x)^2
3 + 7*(1+x)² = (1+3x)² 3 + 7 * (1 + 2x + x²) = 1 + 6x + 9x² 3 + 7 + 14x + 7x² = 1 + 6x + 9x² 9x² - 7x² + 6x - 14x + 1 - 10 = 0 2x² - 8x - 9 = 0 D = (-8)² - 4 * 2 * (-9) = 136