Check my answers? 1. solve the system of equations: -10x-3y=-18 -7x-8y=11 [ a) (-7,-10) ] b) (3-4) c) (-4,-3) d) (2,-1) 2. solve the following system of equations by graphing: -4x+3y=12 -2x+3y=-18 [ a) (2.67,-2) ] b) (1,-5.33) c) (-3,-8) d) (-15.-16) 3. what is the solution to the system of equations? y=3x+7 y-x-9 a) (-1,-10) b) (-17,-8) c) (4,19) [ d) (-8,-17) ]

3. D)

2. D)

1. B)

Step-by-step explanation:

3.

{y = 3x + 7

{y = x - 9

x - 9 = 3x + 7

-3x - 3x

____________

−2x - 9 = 7

+ 9 + 9

__________

−2x = 16

____ __

−2 −2

[Plug this back into both equations above to get the y-coordinate of −17];

__________________________________________________________

2.

{−4x + 3y = 12

{−2x + 3y = −18

−½[−4x + 3y = 12]

{2x - 1½y = −6 >> New Equation

{−2x + 3y = −18

_______________

1½y = −24

____ ____

1½ 1½

[Plug this back into both equations above to get the x-coordinate of −15];

__________________________________________________________

1.

{−10x - 3y = −18

{−7x - 8y = 11

−⅜[−7x - 8y = 11]

{−10x - 3y = −18

{2⅝x + 3y = −4⅛ >> New Equation

_________________

−7⅜x = −22⅛

______ _____

−7⅜ −7⅜

[Plug this back into both equations above to get the y-coordinate of −4]; 

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