math

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i need help with this problem
2x+2y+3z=-1
3x-5y-2z=21
7x+3y+5z=10

• math -

What method have you learned?

• math -

EITHER SUBSTITUTION OR ELIMINATION

• math -

Ok, elimination then

work on the z's

1st times 2 ---> 4x + 4y + 6z = -2
2nd times 3 ---> 9x - 15y - 6z = 63
13x - 11y = 61 (#4)

2nd times 5 ----> 15x - 25y - 10z = 105
3rd times 2 ----> 14x + 6y + 10z = 20
29x - 19y = 125 (#5)

going to be messy .....
#4 times 19 ----> 247x - 209y = 1159
#5 times 11 ----> 319x - 209y = 1375
subtract them
72x = 216
x = 216/72 = 3 , Yeahhh!
back in #4

13(3) - 11y = 61
-11y = 61-39
-11y = 22
y = -2

back in #1
2(3)+2(-2) + 3z = -1
3z = -1 -2
z = -1

x=3 , y=-2 , z=-1

• math -

CAN ANYONE JUST GET ME HEADED IN THE RIGHT
DIRECTION ON THIS PROBLEM
2x+2y+3z=-1
3x-5y-2z=21
7x+3y+5z=10

• math -

And exactly what did you not like about the solution which is staring at you right above you ?????

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