Needed help with this math question.

Question

2x^2 +8x =24

What's the solutions x=?

Answer 1

You'll always get the roots (solution) if you use the Quadratic equation.  If you're not familiar with this just look it up in Wikipedia.  However this equation can be solved by "guessing" at the roots of the equation.

First write the equation as:

x^2 + 4x - 12 = 0   (just divide the 2 through and bring 12 over to the LHS of the equation)  LHS stands for Left-Hand-Side

Ask yourself what two numbers when multiplied together give you -12 but when added together they give 4.

These are the numbers that would go into the following equivalent expression of the above equation.

(x - A) * (x + B) = 0   

This gives you two solutions (or roots) and are A and -B... Hope that helps... Good luck but like I said you can always use the Quadratic Equation to get the same roots.

Mark

 

Answer 2

You can change it like (x+6)(2x-4)=0, thus x =-6 or 2. Using Chinese teaching method, it is very easy to know how to change it from 2x^2 +8x =24 . 

 

Alice