could someone please help me with math?

Question

Solve the equation

 

a²+5a-36=0 

 

a = _______ , _______

Answer 1

(a+9)(a-4) = 0  so  a = {-9, 4}

 

This is why we learn factoring.

Answer 2

Hi Michael,

 

 

Solve the equation


a²+5a-36=0

a = _______ , _______

 

 

To solve this quadratic, we need to factor it.

 

a²+5a-36=0

 

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

since the 2nd term is positive, the larger of the factors must be positive.

this helps narrow down the factors.

We need factors of -36 which add up to 5

 

-1   36  no

-2   18   no

-3    12   -3+12=9 so we are getting closer

-4    9     -4+9=5  YES!!

 

a²+5a-36=0

(a-4)(a+9)=0  now using the zero product property we set each factor equal to zero.

 

a-4=0           a+9=0

a=4              a=-9

 

 

ANSWER:  a=4, a=-9

 

We're done!