13.05 Completing the Square: X^2+20x=10 X^2-4x=8 X^2+5x=3 X^2-9x=5 2x^2-48x=10 X^2+2x=8 X^2-6x=16 X^2-18x=19 X^2+3x=3 X^2+7x=8

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The way these equations are arranged helps.  First only deal with the left handside.  X^2+20x= (x+a)^2 -b where we are looking for a,b You need to know the general formula for (x+a)^2=x^2+2ax+a^2 20x = 2*10x so a will be 10 (x+10)^2= x^2+20x+100 Now lets look at the original question:  X^2+20x=10 we know now that (x+10)^2= x^2+20x+100 Thus X^2+20x=(x+10)^2 -100 So X^2+20x=10 becomes (x+10)^2 -100 =10 (x+10)^2=110 For the other question you need to follow the same logic.

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