Question 119488
original problem: 5x^2-30x+40=0 
work:
5x^2-30x=-40
x^2-6x=-8
x^2-6x+9=-8+9
Factor to get: 
(x-3)^2 = 1
Take the square root of both sides to get;
x-3=1 or x-3=-1
x = 4 or x = 2
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Cheers,
Stan H.