Can you help me with some Algebra problems?

1. Graph the linear system and tell how many solutions it has.

2x-y=5

-x+y=-3

2x-3y=-6

-3y+2x=3

3x+y=1

2y=2-6x

Find x and y by using algebraic method.

3x-2y=10

5x+3y=-15

3x-5y+10=0

-9x+15y=-30

2x-4y=-6

-2x+4y=6

Find x, y, and z.

-3x+4y=-6

5x-3z=-22

3y+2z=-1

Please Help THANKS!!

3 Answers

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  • mom
    Lv 7
    1 decade ago
    Favorite Answer

    For graphing, I like to let first x then y =0, and find the corresponding point. If it's a fraction, I like to use the slope-intercept method.

    1. second one, x=0,y=-3 and y=0, x=3

    first one, y=2x-5, x=0, y=-5 and pick a value for x, find the corresponding y OR start at the intercept and go up 2, to the right 1

    2. x=0, y=1, now let x=any number , say 3, y= -8

    second one; x=0, y=-1, and for the second point, solve for y (this might be easier to do for all the equations)

    -3y=-2x +3. so y= 2/3 x -1

    pick an x value that is divisible by 2 so you won't have fractions. Let x=3, y= 1

    3. y=-3x+1 x=0,y=1 and x=1. y=-2

    the second is also y=-3x + 1 so both equations have the same graph

    4. #1 times 3 , #2 times 2, then add

    9x-6y=30

    10x+6y=-30

    19x=0.

    x=0

    put in one equation and solve for y

    y=2

    5. #1 times 3, then add

    9x-15y=0

    -9x+15y=-30

    0=-30 is a false so there is no solution and the lines are parallel

    6. Same here

    7. rewrite putting in the milling letters with a zero coefficient

    -3x + 4y + 0z = -6

    5x +0y -3z = -22

    0x +3y +2z = -1

    #1 times 5, #2 times 3 and add

    -15x +20y +0z = -30

    15x +0y -9z = -66

    -----------------------------

    20y -9z = -96

    3y + 2z = -1 mult this by 9 and the one above it by 2, add

    40y -18z =-192

    27y +18z = -9

    ------------------

    67y = -201

    y= - 3 sub this in 3y + 2z = -1,

    -9 +2z = -1

    2z = 8

    z=4 sub this in 5x - 3z =-22

    5x - 12 = -22

    5x = -10

    x= -2

    (-2, -3, 4)

    check in -3x + 4y = -6

    6 + 12 = -6. It works

  • Anonymous
    1 decade ago

    well the graphing i can't help with b/c i dont have any graph paper but mostly it would either have 1 solution no solution or infinitely many solutions

    the first is infinitely many

    the second one has no solution

    the third is infinitely many because 0=0

    no help on the fourth sorry i havent gotten there yet but please vote best answer

  • ?
    Lv 4
    1 decade ago

    Check out this best link:www.intmath.com.When you will check out this website you will forget to ask questions.I have helped you so much plz, plz ,plz give me as best answer.Good Luck

    Source(s): As best answer
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