Examples
f(x)=2x2+3x-4f(x)=2x2+3x−4
Step 1
Step 1.1
Complete the square for 2x2+3x-4.
Step 1.1.1
Use the form ax2+bx+c, to find the values of a, b, and c.
a=2
b=3
c=-4
Step 1.1.2
Consider the vertex form of a parabola.
a(x+d)2+e
Step 1.1.3
Find the value of d using the formula d=b2a.
Step 1.1.3.1
Substitute the values of a and b into the formula d=b2a.
d=32⋅2
Step 1.1.3.2
Multiply 2 by 2.
d=34
d=34
Step 1.1.4
Find the value of e using the formula e=c-b24a.
Step 1.1.4.1
Substitute the values of c, b and a into the formula e=c-b24a.
e=-4-324⋅2
Step 1.1.4.2
Simplify the right side.
Step 1.1.4.2.1
Simplify each term.
Step 1.1.4.2.1.1
Raise 3 to the power of 2.
e=-4-94⋅2
Step 1.1.4.2.1.2
Multiply 4 by 2.
e=-4-98
e=-4-98
Step 1.1.4.2.2
To write -4 as a fraction with a common denominator, multiply by 88.
e=-4⋅88-98
Step 1.1.4.2.3
Combine -4 and 88.
e=-4⋅88-98
Step 1.1.4.2.4
Combine the numerators over the common denominator.
e=-4⋅8-98
Step 1.1.4.2.5
Simplify the numerator.
Step 1.1.4.2.5.1
Multiply -4 by 8.
e=-32-98
Step 1.1.4.2.5.2
Subtract 9 from -32.
e=-418
e=-418
Step 1.1.4.2.6
Move the negative in front of the fraction.
e=-418
e=-418
e=-418
Step 1.1.5
Substitute the values of a, d, and e into the vertex form 2(x+34)2-418.
2(x+34)2-418
2(x+34)2-418
Step 1.2
Set y equal to the new right side.
y=2(x+34)2-418
y=2(x+34)2-418
Step 2
Use the vertex form, y=a(x-h)2+k, to determine the values of a, h, and k.
a=2
h=-34
k=-418
Step 3
Find the vertex (h,k).
(-34,-418)
Step 4