Question 392450
(x+5)(x-4)(x+2)>0
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Draw a number line and plot x = -5,-2, and 4
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Check a value from each of the resulting intervals
to see where the solution set is.
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If x= -10 you get -*-*- > 0; false
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If x = -3, you get +*-*- > 0; true, so solutions in (-5,-2)
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If x = 0, you get +*-*+ > 0; false
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If x = 10, you get +*+*+ > 0; true, solutions in (4,+inf)
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Ans: (-5,-2)U(4,+inf)
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Also: solve for x
4x(x-7)-5x(x-6)=-3
4x^2-28-5x^2+30x = -3
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-x^2+30x-25 = 0
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x^2-30x+25 = 0
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x = [30 +- sqrt(900-4*25)]/2
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x = [30 +- sqrt(800)]/2
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x = [30 +- 20sqrt(2)]/2
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x = [15 +- 10sqrt(2)]
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Add:
(2x^2-5xy+y^2)+(-9x^2-2xy-y^2)+(x^2+xy-2y^2)
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= -6x^2-6xy-2y^2
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= -2(3x^2+3xy+y^2)
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Cheers,
Stan H.