Write an equation in intercept form of the parabola that Passes through (-1,40) and x=-5, 4
Question
Answer:
At first I didn't understand what you meant by "x = -5, 4. What I think you meant was "the horizontal intercepts of the graph of this parabola are (-5,0) and (4,0)."If this is the case, then the equation of the parabola is found as follows:
y=ax^2 + bx + c for the point (-5, 0) is 0=a(-5)^2 + b(-5) + c
for the point (4,0) is 0 = a(4)^2 +b(4) + c
for the point (-1,40) is 40 = a(-1)^2 + b(-1) + c
Here we have 3 equations in 3 unknowns, which is enough to solve for {a,b,c}. Using matrix algebra, I found that a= -2, b= -2, c= 40.
Then one equation for this parabola would be:
y = -2x^2 - 2x + 40
Check this by substitution. Does the point (-5,0) satisfy y = -2x^2 - 2x + 40?
Yes. So y = -2x^2 - 2x + 40 is the general form of the equation of this parabola. To express it in intercept form, factor y = -2x^2 - 2x + 40.
solved
general
11 months ago
2359