quadratic equations

Question

X²+2x-8=0

Answer 1

There are 3 different ways to factor a trinomial:

 

Quadratic formula (works every time but usually tedious)

Completing the square (works every time but usually tedious)

AC method (doesn't work every time but very quick especially with small numbers)

 

Since these numbers we have are very very small, lets use the AC method.

The A, B, and C terms must all be on one side, and they are. AC is A*C, so that is 8x².

You need to find two numbers that are factors of this, but at the same time must add or subtract to get B, or 2. We can tell now that this will not work out, so we will have to use one of the other two methods.

 

The quadratic formula is, like stated above, x= [(-)b±(√b2-4ac)]/2a

 

x=-[-2±(√22-4(1)(-8)]/2

x=[-2±(√4--32)]/2

x=[-2±√36]/2

x=(-2±6)/2

x=2 and x=-4

 

Sometimes trinomials just end up with one answer, if the exponent 2 happens to go away, but 9 times out of 10, you will have 2 answers.

 

 

 

Answer 2

x²+2x-8=0

 

a=1   b=2   c=-8

 

Quadratic Equation: x= [(-)b±(√b²-4ac)]/2a

 

 

x=-[-2±(√2²-4(1)(-8)]/2      

 

x=[-2±(√4-^-32)]/2

 

x=[-2±√36]/2

 

x=(-2±6)/2

 

x=2 and x=-4

Answer 3

x^2+2x-8=0

(x+4)(x-2)=0

x+4=0

x=-4

x-2=0

x=2