SOLUTION: Please help!I thought I had the correct answers, but I got them wrong. find the intercepts and traces for the graph 7x + 3y-z = 42 x-intercept (I had 5,0,0) y-intercept ( I had

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Question 607161: Please help!I thought I had the correct answers, but I got them wrong.
find the intercepts and traces for the graph 7x + 3y-z = 42
x-intercept (I had 5,0,0) y-intercept ( I had 0,2,-1) z-intercept (I had 0,0,-1)
xy trace (I had 5,2,0) yz trace (I had (0,2,-1) xz trace (I had 5,0,1)

thank you so much!

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
x-intercept: plug in y = 0 and z = 0 and solve for x

7x + 3y-z = 42

7x + 3(0)-0 = 42

7x + 0 - 0 = 42

7x = 42

x = 42/7

x = 6

So the x-intercept is (6,0,0)

-------------------------------------------------------
y-intercept: plug in x = 0 and z = 0 and solve for y

7x + 3y-z = 42

7(0) + 3y-0 = 42

0 + 3y - 0 = 42

3y = 42

y = 42/3

y = 14

So the y-intercept is (0,14,0)

-------------------------------------------------------
z-intercept: plug in x = 0 and y = 0 and solve for z

7x + 3y-z = 42

7(0) + 3(0)-z = 42

0 + 0 - z = 42

-z = 42

z = -42

So the z-intercept is (0,0,-42)
====================================================================================
xy trace: Plug in z = 0

7x + 3y-z = 42

7x + 3y - 0 = 42

7x + 3y = 42

So the xy trace is 7x + 3y = 42 (note: this is a line and NOT a point)
===================================================================================
yz trace: plug in x = 0

7x + 3y-z = 42

7(0) + 3y-z = 42

0 + 3y-z = 42

3y-z = 42

So the yz trace is 3y-z = 42

===================================================================================
xz trace: plug in y = 0

7x + 3y-z = 42

7x + 3(0)-z = 42

7x + 0 -z = 42

7x - z = 42

So the xz trace is 7x - z = 42

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