Use the given roots to write the equation in factored form. Then multiply and simplify to obtain the standard form.
Example Solution: x^2+3x-40=0
Practice makes perfect
We can write a quadratic equation in factored form using the given roots. Then we will change it to standard form by multiplying the factors.
Factored Form:& a(x-p)(x-q)=0
Standard Form:& ax^2+bx+c=0
In the factored form, p and q are the roots of the equation. Since we are told the roots are - 8 and 5, we can partially write the factored form of our equation.
a( x-( - 8 ) ) ( x-5 )=0
⇕
a( x+ 8 ) ( x-5 )=0
Since a does not have any effect on the roots, we can choose any value. For simplicity we will let a=1.
1( x+ 8 ) ( x-5 )=0 ⇔ ( x+ 8 ) ( x-5 )=0
Finally, let's use the Distributive Property to obtain the standard form.
