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Can somebody explain this to me please?

OCR C1&2 Exercise 1E Question 12

There are some values of a, b and c for which the equation ax + by + c = 0 does not represent a straight line. Give an example of such values.

Once I've had it explained to me I'll probably understand it.

The answer at the back gives the example:
a = 0
b = 0
c = 1

Can you give me some other examples?

Thanks

Reply 1

Bleak Lemming

Am I right in saying if the left side does not equal to 0 then the line is not straight?

Thus another example could be
a = 0
b = 0
c = any number other than 0

Reply 2

Kasc

a=0, b=0 and c is any value except 0?

Reply 3

Bleak Lemming

Original post by Kasc

a=0, b=0 and c is any value except 0?

is that an answer or a question?

Reply 4

$Avatar for Get me off the £\?%!^@ computer$

Get me off the £\?%!^@ computer

Original post by Bleak Lemming

Am I right in saying if the left side does not equal to 0 then the line is not straight?

If 0=1 the line is anything you want it to be.

Reply 5

LeeC

Re-arranging:

y=-(a/b)x - (c/b)

When b is 0 these terms are undefined, I don't get it...

Reply 6

Bleak Lemming

Original post by Get me off the £\?%!^@ computer

If 0=1 the line is anything you want it to be.

Think i get it thx, so the same applies if 0 = 2, or 5, or 38383

Reply 7

$Avatar for Get me off the £\?%!^@ computer$

Get me off the £\?%!^@ computer

Original post by Bleak Lemming

Think i get it thx, so the same applies if 0 = 2, or 5, or 38383

Yes.

If a=0, b=0 and c=/=0 then ax+by+c=0 is not an equation of a straight line.

Reply 8

crocker710

This is because if you just had the +C part of an equation it would look like this

4 = 4
5 = 5
6 = 6
ect.

so if you were given values for x or y you would not be able to form a line on a graph.