Question 192288
1) Solve by factoring:
x^2 - 9x = -20
x^2-9x+20=0
(x-5)(x-4)=0
x-5=0
x=5 ans.
x-4=0
x=4 ans.
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2) Solve using the quadratic formula:
3x^2 - 2x = 15x - 10
3x^2-2x-15x+10=0
3x^2-17x+10=0
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
x=(17+-sqrt[-17^2-4*3*10])/2*3
x=(17+-sqrt[289-120])/6
x=(17+-sqrt169)/6
x=(17+-13}/6
x=(17+13)/6
x=30/6
x=5 ans.
x=(17-13)/6
x=4/6
x=2/3 or .6667 ans. 
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3) Solve using the quadratic formula:
x^2 - 3x - 23 = 5
x^2-3x-23-5=0
x^2-3x-28=0
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
x=(3+-sqrt[-3^2-4*1*-28])/2*1
x=(3+-sqrt[9+112])/2
x=(3+-sqrt 121]/2
x=(3+-11)/2
x=(3+11)/2
x=14/2
x=7 ans.
x=(3-11)/2
x=-8/2
x=-4 ans.