Find which of the following equations are quadratic :
7x3 - 2x2 + 10 = (2x - 5)2
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⇒ 7x3 - 2x2 + 10 = 4x2 + 25 - 20x
⇒ 7x3 - 2x2 - 4x2 + 10 - 25 + 20x = 0
⇒ 7x3 - 6x2 - 15 + 20x = 0 which is not of the form ax2 + bx + c = 0.
∴ Given equation is not a quadratic equation.
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5x2 - 8x = -3(7 - 2x)
(x - 4)(3x + 1) = (3x - 1)(x + 2)
Is x = 5 a solution of the equation x2 - 2x - 15 = 0 ?
Is x = -3 a solution of the equation 2x2 - 7x + 9 = 0 ?