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Question

solve the following system
x-2y+3z+=9
-x+3y =-4
2x-5y+5z=17

Answer 1

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Take any 2 equations and multiply all of the terms or one or both by numbers that will make one of the terms in each equation have the same coefficient. Now subtract one from the other and the term will disappear. Now take the resulting equation and do the same with it against the third. Keep doing this until you are down to one term and solve for the variable. Now substitute the variable into the equation and solve for the other variables.

Answer 2

There are several ways to solve this system. My favorite method (when it will work nicely) is just to add the different equations together. The thing you're going for when you add them together is to be able to eliminate one or more variables. First, let's get rid of z.
1. Multiply the first & third equation by something so that when added together they will eliminate the z variable. Since you have 3z and 5z, your least common multiple for z is 15.
Multiply the first equation by 5, and the second by -3 giving you:
5x -10y +15z =45
-6x +15y -15z =-51

2. Now add those together giving you:
-1x + 5y = -6

3. Multiply that equation by -1, and then add it to the original 2nd equation:
x -5y = 6
-x + 3y =-4
Giving you:
-2y = 2
y=-1

4. Go back, and plug the y value into the original 2nd equation giving you: -x +3(-1) = -4 Solve for x, giving you x=1

5. Now plug the x & y values into the orignal eq 1 or 3, and solve for z. You will get z=2

ANSWERS:
x = 1
y = -1
z = 2

Answer 3

Add the 1st 2 equations and get
4) y + 3z = 5

Add twice the 2nd equation to the 3rd and get
5) y + 5z = 9

Subtract 4) from 5) and get 2z = 4, z = 2.

Plug z = 2 into 5) and get y = -1

Plug -1 into 2) and get x = 1.

Answer 4

Pay a tutor.