Abiologist found a system of equations to her calculate the growth of bacteria. the functions she found y=2x2−21y=2x2-21 & y=9x−3y=9x-3 part a – explain how would she find the answer to her system of equations without using graphing technology. part b- explain how to solve using graphing technology. how do you know the where the results of the system are?

Did you get the answer to Part B? we have the same problem.

The answer for Part A is this,

y=2x^2-15.  and y=3x-6

2x^2-15=3x-6

(Add 15 to both sides)

2x^2-3x-9=0

(Factor)

(2x+3)(x-3)

(Set equal to zero on both sides to solve)

2x+3=0          and        x-3=0

Subtract 3 from both sides for the first equation.
Add 3 to both sides in the second equation.

2x=-3      and      x=3

Divide by 2 on both sides for the first equation ONLY.

To get x=-3/2

THE TWO X VALUES ARE

X=-3/2 and X=3