ECON 11A Study Guide - Quiz Guide: Quadratic Equation
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Fall 2016: (5 pts) solve the equation: (i) cross multiply: x + 5. 3x 1 (ii) expand both sides of the equation: 6x2 + x 1 = 3x2 + 13x 10 = 3x2 12x + 9 = 0 (iv) solve quadratic equation by factoring 3x2 12x + 9 = 0 = 3(x2 4x + 3) = 0 = 3(x 1)(x 3) = 0 = x1 = 1 and x2 = 3. = 3: (5 pts) solve the pair of equations: 7x + 3y = 11 (i) multiply rst equation by 3 and second equation by 2: (cid:27) (cid:26) 15x + 6y = 9. 7x + 3y = 11 (ii) subtract second equation from rst equation: (15x + 6y = 9) (14x + 6y = 22) x + 0 y = 13 (iii) substitute x = 13 into (original) rst equation: = lim x 1 limx 1(x + 2) limx 1(x + 1)
