Explanation: Quadratic formula (shown in attached image) is used to find the solutions to second degree equations.
Let'as check our choices: Choice A: 5x³ + 2x - 4 = 2x² 5x³ + 2x - 4 - 2x² = 0 This is an equation of third degree. Therefore, this option is incorrect.
Choice B: x² - 6x - 7 = 2x x² - 6x - 7 - 2x = 0 x² - 8x - 7 = 0 This is a second degree equation. Therefore, this choice is correct
Choice C: 2x² - 3x + 10 = 2x² + 21 2x² - 3x + 10 - 2x² - 21 = 0 -3x - 11 = 0 This is a first degree equation. Therefore, this choice is incorrect
Choice D: 5x² - 3x + 10 = 2x² 5x² - 3x + 10 - 2x² = 0 3x² - 3x + 10 = 0 This is a second degree equation. Therefore, this choice is correct
