Quadratic equation

Determine the numbers b, c that the numbers x1 = -1 and x2 = 3 were roots of quadratic equation:

−3x2+bx+c=0


Correct result:

b =  6
c =  9

Solution:

a=−3 b=−ax1−ax2=6
c=ax1x2=9 −3x2+6x+9=0

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