Examples
(2,3) , (-1,-5)
Step 1
The general equation of a parabola with vertex (h,k) is y=a(x-h)2+k. In this case we have (2,3) as the vertex (h,k) and (-1,-5) is a point (x,y) on the parabola. To find a, substitute the two points in y=a(x-h)2+k.
-5=a(-1-(2))2+3
Step 2
Step 2.1
Rewrite the equation as a(-1-(2))2+3=-5.
a(-1-(2))2+3=-5
Step 2.2
Simplify each term.
Step 2.2.1
Multiply -1 by 2.
a(-1-2)2+3=-5
Step 2.2.2
Subtract 2 from -1.
a(-3)2+3=-5
Step 2.2.3
Raise -3 to the power of 2.
a⋅9+3=-5
Step 2.2.4
Move 9 to the left of a.
9a+3=-5
9a+3=-5
Step 2.3
Move all terms not containing a to the right side of the equation.
Step 2.3.1
Subtract 3 from both sides of the equation.
9a=-5-3
Step 2.3.2
Subtract 3 from -5.
9a=-8
9a=-8
Step 2.4
Divide each term in 9a=-8 by 9 and simplify.
Step 2.4.1
Divide each term in 9a=-8 by 9.
9a9=-89
Step 2.4.2
Simplify the left side.
Step 2.4.2.1
Cancel the common factor of 9.
Step 2.4.2.1.1
Cancel the common factor.
9a9=-89
Step 2.4.2.1.2
Divide a by 1.
a=-89
a=-89
a=-89
Step 2.4.3
Simplify the right side.
Step 2.4.3.1
Move the negative in front of the fraction.
a=-89
a=-89
a=-89
a=-89
Step 3
Using y=a(x-h)2+k, the general equation of the parabola with the vertex (2,3) and a=-89 is y=(-89)(x-(2))2+3.
y=(-89)(x-(2))2+3
Step 4
Step 4.1
Remove parentheses.
y=(-89)(x-(2))2+3
Step 4.2
Multiply -89 by (x-(2))2.
y=-89⋅(x-(2))2+3
Step 4.3
Remove parentheses.
y=(-89)(x-(2))2+3
Step 4.4
Simplify (-89)(x-(2))2+3.
Step 4.4.1
Simplify each term.
Step 4.4.1.1
Multiply -1 by 2.
y=-89(x-2)2+3
Step 4.4.1.2
Rewrite (x-2)2 as (x-2)(x-2).
y=-89((x-2)(x-2))+3
Step 4.4.1.3
Expand (x-2)(x-2) using the FOIL Method.
Step 4.4.1.3.1
Apply the distributive property.
y=-89(x(x-2)-2(x-2))+3
Step 4.4.1.3.2
Apply the distributive property.
y=-89(x⋅x+x⋅-2-2(x-2))+3
Step 4.4.1.3.3
Apply the distributive property.
y=-89(x⋅x+x⋅-2-2x-2⋅-2)+3
y=-89(x⋅x+x⋅-2-2x-2⋅-2)+3
Step 4.4.1.4
Simplify and combine like terms.
Step 4.4.1.4.1
Simplify each term.
Step 4.4.1.4.1.1
Multiply x by x.
y=-89(x2+x⋅-2-2x-2⋅-2)+3
Step 4.4.1.4.1.2
Move -2 to the left of x.
y=-89(x2-2⋅x-2x-2⋅-2)+3
Step 4.4.1.4.1.3
Multiply -2 by -2.
y=-89(x2-2x-2x+4)+3
y=-89(x2-2x-2x+4)+3
Step 4.4.1.4.2
Subtract 2x from -2x.
y=-89(x2-4x+4)+3
y=-89(x2-4x+4)+3
Step 4.4.1.5
Apply the distributive property.
y=-89x2-89(-4x)-89⋅4+3
Step 4.4.1.6
Simplify.
Step 4.4.1.6.1
Combine x2 and 89.
y=-x2⋅89-89(-4x)-89⋅4+3
Step 4.4.1.6.2
Multiply -89(-4x).
Step 4.4.1.6.2.1
Multiply -4 by -1.
y=-x2⋅89+4(89)x-89⋅4+3
Step 4.4.1.6.2.2
Combine 4 and 89.
y=-x2⋅89+4⋅89x-89⋅4+3
Step 4.4.1.6.2.3
Multiply 4 by 8.
y=-x2⋅89+329x-89⋅4+3
Step 4.4.1.6.2.4
Combine 329 and x.
y=-x2⋅89+32x9-89⋅4+3
y=-x2⋅89+32x9-89⋅4+3
Step 4.4.1.6.3
Multiply -89⋅4.
Step 4.4.1.6.3.1
Multiply 4 by -1.
y=-x2⋅89+32x9-4(89)+3
Step 4.4.1.6.3.2
Combine -4 and 89.
y=-x2⋅89+32x9+-4⋅89+3
Step 4.4.1.6.3.3
Multiply -4 by 8.
y=-x2⋅89+32x9+-329+3
y=-x2⋅89+32x9+-329+3
y=-x2⋅89+32x9+-329+3
Step 4.4.1.7
Simplify each term.
Step 4.4.1.7.1
Move 8 to the left of x2.
y=-8⋅x29+32x9+-329+3
Step 4.4.1.7.2
Move the negative in front of the fraction.
y=-8x29+32x9-329+3
y=-8x29+32x9-329+3
y=-8x29+32x9-329+3
Step 4.4.2
To write 3 as a fraction with a common denominator, multiply by 99.
y=-8x29+32x9-329+3⋅99
Step 4.4.3
Combine 3 and 99.
y=-8x29+32x9-329+3⋅99
Step 4.4.4
Combine the numerators over the common denominator.
y=-8x29+32x9+-32+3⋅99
Step 4.4.5
Simplify the numerator.
Step 4.4.5.1
Multiply 3 by 9.
y=-8x29+32x9+-32+279
Step 4.4.5.2
Add -32 and 27.
y=-8x29+32x9+-59
y=-8x29+32x9+-59
Step 4.4.6
Move the negative in front of the fraction.
y=-8x29+32x9-59
y=-8x29+32x9-59
y=-8x29+32x9-59
Step 5
The standard form and vertex form are as follows.
Standard Form: y=-89x2+329x-59
Vertex Form: y=(-89)(x-(2))2+3
Step 6
Simplify the standard form.
Standard Form: y=-89x2+329x-59
Vertex Form: y=-89(x-2)2+3
Step 7