Solving polynomials

Question

Solve 

28+5a-12a^2=0

 

Answer 1

Lets rearrange the terms in the polynomial in descending order.  This means that the term with the highest exponent value comes first.

 

-12a² + 5a + 28 = 0

 

We will use the quadratic formula:  x is not to be confused with a in the formula.

 

x = (-b ± √(b² - 4ac)) / 2a

 

x = (-5 ± √(5² - 4(-336)) / -24

 

x = (-5 ± √(25 + 1344)) / -24

 

x = (-5 ± 37) / -24

 

 

x₁ = a₁ = -1.33

x₂ = a₂ =  1.75