If x + y = 7 and 2x - y = 2, then y - ?

(3,4)

Step-by-step explanation:

This system is already setup for linear combination/elimination (don't know what your class calls it).

The reason I say this is because if you add the equations together the variable y will be eliminated giving you a chance to solve for x.

Let's do that:

 x+y=7

2x-y=2

Add.

3x   =9

Divide both sides by 3:

 x    =3

Using one of the equations (doesn't matter; you choose) along with x=3 we can find y.

I choose x+y=7 with x=3.

x+y=7 with x=3:

3+y=7

Subtract 3 on both sides:

  y=7-3

Simplify:

  y=4

The solution is (x,y)=(3,4).

Let's check our solution by plugging it in:

x+y=7

3+4=7

   7=7 is true.

2x-y=2

2(3)-4=2

6-4=2

2=2 is true.

Since both equations are true for (x,y)=(3,4), then (3,4) is definitely a solution.

So we have solution confirmation.

the red lines denote the population of the bacteria after 35 hours. that would be 2,409.24. the y-intercept is the blue line which is 800 because that is the starting point. the equation used to make the graph is 800(1.032)^h, where h is the number of hours.

step-by-step explanation:

i hope this is what you were looking for.

see attached graph