Find the Equation Given the Roots 3 , 6

$3$ , $6$

Step 1

Roots are the points where the graph intercepts with the x-axis $(y = 0)$ .

$y = 0$ at the roots

Step 2

The root at $x = 3$ was found by solving for $x$ when $x - (3) = y$ and $y = 0$ .

The factor is $x - 3$

Step 3

The root at $x = 6$ was found by solving for $x$ when $x - (6) = y$ and $y = 0$ .

The factor is $x - 6$

Step 4

Combine all the factors into a single equation.

$y = (x - 3) (x - 6)$

Step 5

Multiply all the factors to simplify the equation $y = (x - 3) (x - 6)$ .

Expand $(x - 3) (x - 6)$ using the FOIL Method.

Apply the distributive property.

$y = x (x - 6) - 3 (x - 6)$

Apply the distributive property.

$y = x \cdot x + x \cdot - 6 - 3 (x - 6)$

Apply the distributive property.

$y = x \cdot x + x \cdot - 6 - 3 x - 3 \cdot - 6$

Simplify and combine like terms.

Simplify each term.

Multiply $x$ by $x$ .

$y = x^{2} + x \cdot - 6 - 3 x - 3 \cdot - 6$

Move $- 6$ to the left of $x$ .

$y = x^{2} - 6 \cdot x - 3 x - 3 \cdot - 6$

Multiply $- 3$ by $- 6$ .

$y = x^{2} - 6 x - 3 x + 18$

Subtract $3 x$ from $- 6 x$ .

$y = x^{2} - 9 x + 18$

Step 6