Equation in TWO unknowns!!

[匿名]

2009-09-03 2:56 am

Please help me to solve/teach this hard equation??

If 3x-y+k=0, which passes through A(2,9) and cuts the x-axis and the y-axis at the point B and C respectively:

1) Find the coordinates of B and C

更新1:

One mpre thing to ask: 2) How can I draw line in the graphical method to solve simultaneous linear equations in two unkown?? At first, I need to fill in a table...something like x can be a, b, c and y can be d, e, f... And then, I need to put the points to the graph! But I don't know how~

回答 (1)

Prof. Physics

2009-09-03 3:24 am

✔ 最佳答案

Since 3x - y + k = 0 passes through A(2 , 9)

Put A(2 , 9) into the equation:

3(2) - 9 + k = 0

k = 3

Therefore, the equation becomes: 3x - y + 3 = 0

For it passes through B, we put y = 0

3x - 0 + 3 = 0

x = -1

So, B(-1 , 0)

For C, put x = 0

0 - y + 3 = 0

y = 3

So, C(0 , 3)

參考: Physics king

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