Question 143252
I BELIEVE YOUR ANSWERS ARE ROUNDED NUMBERS & DON'T WORK OUT IN THE PROOF:
29*31/(29=31=15
899/60=15
14.98=/15
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X(X+2)/(X+X+2)=15
(X^2+2X)/(2X+2)=15
X^2+2X=15(2X+2)
X^2+2X=30X+30
X^2+2X-30X-30=0
X^2-28X-30=0
USING THE QUADRATIC EQUATION {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}WE GET:
X=(28+-SQRT[28^2-4*1*-30])/2*1
X=(28+-SQRT[784+120])/2
X=(28+-SQRT904)/2
X=(28+-30.0666)/2
X=(28+30.0666)/2
X=58.0666/2
X=29.0333 FOR ONE MARY'S 'MOW ALONE' TIME.
29.0333+2=31.0333 FOR SDARA'S MOW ALONE TIME.
PROOF:
29.0333*31.0333/(29.0333+31.0333)=15
900.999/60.0666=15
15.0000001~15