General Form
f(x) = ax2 + bx + c
Standard Form
f(x) = a (x - h)2 + k
Transforming Quadratic
Functions from
General Form
to Standard Form
STEPS:
1. Factor out a from the first two terms.
2. Complete the square.
3. Factor and combine.
f(x) = ax2 + bx + c
Step 1: Factor out a from the first two terms.
f(x) = a (x2 +
𝑏𝑥
𝑎
) + c
Step 2: Complete the square.
f(x) = a [x2 +bx + (
𝑏
𝑎
𝑥)2] + c - a(
𝑏
2𝑎
)2
f(x) = a [x2 + bx +(
𝑏
𝑎
𝑥)2] + c -
𝑎𝑏2
4𝑎2
f(x) = a [x2 + bx +(
𝑏
𝑎
𝑥)2] + c -
𝑏2
4𝑎
Step 3: Factor and combine.
f(x) = a (x +
𝑏
2𝑎
)2 +
4𝑎𝑐−𝑏2
4𝑎
h= -
𝑏
2𝑎
and k =
4𝑎𝑐−𝑏2
4𝑎
f(x)=a(x-h)2 + k
Examples
f(x) = x2 – 8x + 3 a = 1
f(x) = (x2 – 8x) + 3
f(x) = (x2 –8x + (
8
2
)2) + 3 - (
8
2
)2
f(x) = (x2 – 8x + (4)2) + 3 – (4)2
f(x) = (x2 – 8x + 16) + 3 – 16
f(x) = (x – 4)2 – 13
f(x) = 2 x2 + 5𝑥 – 1 a = 2
f(x) = 2 (x2 +
5
2
𝑥 ) – 1
f(x) = 2 [x2 +
5
2
𝑥 + (
25
16
)] – 1 -
25
8
f(x) = 2 (x+
5
4
)2 + (
−8−25
8
)
f(x) = 2 (x+
5
4
)2 + (
−33
8
)
1. f(x) = x2 - 12x + 4
2. f(x) = 5x2 + 20x -12
3. f(x) = x2 + 3x + 36
4. f(x) = 4x2 + 2x + 9
5. f(x) = 3x2 + 6x + 2
Activity
Transform the following quadratic functions into standard form.

Transforming Quadratic Functions from General Form to Standard Form

  • 2.
    General Form f(x) =ax2 + bx + c
  • 3.
    Standard Form f(x) =a (x - h)2 + k
  • 4.
  • 5.
    STEPS: 1. Factor outa from the first two terms. 2. Complete the square. 3. Factor and combine.
  • 6.
    f(x) = ax2+ bx + c Step 1: Factor out a from the first two terms. f(x) = a (x2 + 𝑏𝑥 𝑎 ) + c
  • 7.
    Step 2: Completethe square. f(x) = a [x2 +bx + ( 𝑏 𝑎 𝑥)2] + c - a( 𝑏 2𝑎 )2 f(x) = a [x2 + bx +( 𝑏 𝑎 𝑥)2] + c - 𝑎𝑏2 4𝑎2 f(x) = a [x2 + bx +( 𝑏 𝑎 𝑥)2] + c - 𝑏2 4𝑎
  • 8.
    Step 3: Factorand combine. f(x) = a (x + 𝑏 2𝑎 )2 + 4𝑎𝑐−𝑏2 4𝑎 h= - 𝑏 2𝑎 and k = 4𝑎𝑐−𝑏2 4𝑎 f(x)=a(x-h)2 + k
  • 9.
  • 10.
    f(x) = x2– 8x + 3 a = 1 f(x) = (x2 – 8x) + 3 f(x) = (x2 –8x + ( 8 2 )2) + 3 - ( 8 2 )2 f(x) = (x2 – 8x + (4)2) + 3 – (4)2 f(x) = (x2 – 8x + 16) + 3 – 16 f(x) = (x – 4)2 – 13
  • 11.
    f(x) = 2x2 + 5𝑥 – 1 a = 2 f(x) = 2 (x2 + 5 2 𝑥 ) – 1 f(x) = 2 [x2 + 5 2 𝑥 + ( 25 16 )] – 1 - 25 8 f(x) = 2 (x+ 5 4 )2 + ( −8−25 8 ) f(x) = 2 (x+ 5 4 )2 + ( −33 8 )
  • 12.
    1. f(x) =x2 - 12x + 4 2. f(x) = 5x2 + 20x -12 3. f(x) = x2 + 3x + 36 4. f(x) = 4x2 + 2x + 9 5. f(x) = 3x2 + 6x + 2 Activity Transform the following quadratic functions into standard form.