3n^2-2n-5=0

Question

solving equations by factoring

Answer 1

Hi Julian,

 

3n²-2n-5=0
solving equations by factoring

 

The process I use is called the Double Slide.

 

Multiply the coefficient of the 1st term by the last term

 

n²-2n-5(3)

n²-2n-15  

 

Since the last term is negative, one factor must be negative and one positive

since the 2nd term is negative, the largest factor must be negative.

 

So we need factors of -15 which add to -2

 

1    -15    no

3     -5     3+-5=-2  YES!

 

n2-2n-15

(n+3)(n-5)        since we multiplied by 3 before we have to divided by 3 now

(n+3/3)(n-5/3)  simplify

(n+1)(n-5/3)   since 5/3 cannot be reduced, we slide the 3 before the n to complete the factor

(n+1)(3n-5)

 

ANSWER:  The factors are (n+1)(3n-5)

 

Hope this helps you understand the process so you can apply it to other problems.