標題:
math question 20p
發問:
1.solve each of the following equations.(express the answers as surds in their simplest form or in the form of a+bi if necessary, where a and b are real numbers.)a)4x^2-12x-15=0b)4x^2-12x+15=02.a)let k be a constant .express the discriminant of the quation x^2=7(x-k) in terms of k.b) if the equations has no... 顯示更多 1.solve each of the following equations.(express the answers as surds in their simplest form or in the form of a+bi if necessary, where a and b are real numbers.) a)4x^2-12x-15=0 b)4x^2-12x+15=0 2.a)let k be a constant .express the discriminant of the quation x^2=7(x-k) in terms of k. b) if the equations has no real roots, find the range of values of k.
最佳解答:
1(a) 4x^2 - 12x - 15 = 0 x = [12 ± √(144 + 240)]/8 x = [12 ± √384]/8 x = [3 ± 2√6]/2 (b) 4x^2 - 12x + 15 = 0 x = [12 ± √(144 - 240)]/8 x = [12 ± √96i]/8 x = [3 ± √6i]/2 2(a) discriminant = 49 - 28k (b) discriminant = 49 - 28k k > 49/28 or k > 7/4
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