Sign In
To complete the square, add and subtract the square of half the coefficient to x.
Consider the equation's constant.
Use the parabola's symmetry to find another point that has a y-coordinate of 7.
Equation: y=(x-(- 5/2))^2+3/4
Vertex: (- 5/2,3/4)
7
Third point: (- 5,7)
Diagram:
The reasons why we complete the square is so that we can rewrite the function in graphing form. In this form its easier to determine the vertex.
Graphing Form:& y=a(x- h)^2+ k
Vertex:& ( h, k)
LHS+(5/2)^2=RHS+(5/2)^2
Commutative Property of Addition
Split into factors
a^2+2ab+b^2=(a+b)^2
(a/b)^m=a^m/b^m
LHS-25/4=RHS-25/4
a = 4* a/4
Subtract fractions
a=- (- a)
Having written the function in graphing form, we can identify the vertex. Graphing Form:& y=(x-( - 5/2))^2+ 3/4 Vertex:& ( - 5/2, 3/4)
In any function the y-intercept is given by its constant. If we examine the function, we can identify the function's constant as 7.
Examining the function, we see that the x^2-term's coefficient is positive. This means that the parabola must open upwards. Let's plot the vertex and y-intercept from Parts A and B. Let's also include the parabola's line of symmetry, which is a vertical line through the parabola's vertex.
The third point is at (- 5,7). Now we can draw an accurate parabola.