Question 986737
make it the form of Ax^2+Bx+C=0
x^2+7x-9=0
no factors of 9 make 7.
Use quadratic formula
A=1
B=7
C=9
x=(1/2A) (-B +/- sqrt (B^2-4AC)
=(1/2)(-7+/- sqrt (49+36)); 4 (1)(-9) and you are subtracting this.
=(1/2)(-7+sqrt 85); (1/2) (-7-sqrt (85))
numerically, about (0.50(2.22) and (0.5)(16.22)
x=1.1, - 8.11 (approx)
{{{graph(300,200,-10,10,-10,10,x^2+7x-9)}}}
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A=5
B=3
C=-19.  They are the coefficients of the x^2, x , and constant respectively.
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Quadratic formula has a +/- square root term. That means there will be two answers, one by adding it to the rest of the equation, the other by subtracting it.
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They all have two roots BUT, a root may repeat, so there is only one root.  This graphs "bounce" where it touches the x-axis in one place.  Roots may also be complex (imaginary), so they do not cross the x-axis.  These are important to realize.  If one asks for roots of a quadratic equation, are complex roots considered? Are roots that repeat (x+2)^2=0 considered?