How would you determine if the points A (2, -5) and B (5, 2) lie on the straight line y = 3x - 5?

Key in your responses in "Comments".

Remember to enter your group number.

## Pages

- Home
- Mathematics Framework
- Habits of Mind
- Wheel of Reasoning
- Tips to do well in Maths
- Online Platforms
- Homework Monitoring
- Info Gathering
- Alternative Assessment 1 (Info)
- Viva Voce Practice 1
- Viva Voce Practice 2
- Alternative Assessment 1: Viva Voce
- Real Numbers in Operation 1
- Real Numbers in Operation 2
- Significant Figures
- Algebra: Expansion
- Algebra: Factorisation
- Algebra: Algebraic Fractions
- Algebra: Solving Equations

If A (2, -5) lie on y=3x-5,

ReplyDelete-5=3(2)-5

=6-5

=1

Therefore, they do not lie on the straight line y=3x-5

Group 2

DeleteGood. So how would you describe your approach in words?

Deletesubstitute x and y into the equation, and since it comes out as -5=1, it does not lie on the line

Deletesubstitute the x and y value of the different points into the equation

ReplyDeleteGroup 4

DeleteYou are on the right track, but the description is incomplete.

DeleteWhat would you do after substituting the values?

Use grapher

ReplyDelete(group 1)

This is a good suggestion when you do daily practices.

DeleteHow would you use graphed?

Describe.

It is not on the line. We can find this out because they give us the formula, we can just substitute the points (X or Y) in the formula to find out the co-ordinates. Group 3

ReplyDeleteWhich formula are you referring to?

DeleteElaborate.

me

ReplyDelete?

Delete?

Delete1) Calculate equation in similar method to Q3 on page 29

ReplyDelete2) Draw out a graph

3) I still think gradient works but may not be the fastest method

Grp4

First find out the gradient of the two points to see if it is 3 because in y=3x-5, 3 is the gradient.

ReplyDeleteAfter calculation we find out that the gradient is 1, which is not the same.

Therefore the two points do not lie on the straight line y=3x-5.

(Group 1)

DeleteRia, read the question again.

DeleteIs the question asking us to compare the line formed by the given points or it's just asking us to check if the points A and B lie on the straight line?

The gradient of y = 3x - 5 is 3. The gradient of the points A (2, -5) and B (5, 2) has a gradient of 2 1/3.

ReplyDeleteWe can draw the graph on grapher or the actual graph.

We can use the formula y=mx+c, for points A (2, -5) and B (5, 2), it is y= 2 1/3x - 9 2/3 and not y=3x-5

Group 3

Prateek, read the question again.

DeleteIs the question asking us to compare the line formed by the given points or it's just asking us to check if the points A and B lie on the straight line?

So, if you have clarity of the question, what would you do if you are using grapher?

Alternatively, without the use of Grapher, what would you do? (i.e. under assessment condition)

By finding out the gradient or substituting x and y values into the equation.

ReplyDeleteGroup 3.

Nishtha, read the question again.

DeleteIs the question asking us to compare the line formed by the given points or it's just asking us to check if the points A and B lie on the straight line?

I still standing on gradient. I don't see any methods honestly.

ReplyDeleteSo standard finding gradient of 2 points y1-y2/x1-x2 which will give 2+1/3

If equation is y=3x -5,

3 --> gradient

Since gradient is different, they cannot be possible on the same line

Group 4 :P

Yew Chong,

DeleteIf we are comparing lines, yes, gradient would be helpful.

Read the question carefully.

Is the question asking us to compare the LINE formed by the given points or it's just asking us to check if the POINTS A and B lie on the straight line?

We can find out if it lies on the given line because the formula is given, so we can just substitute the points in the formula to find out the co-ordinates.

ReplyDeleteKai Heng Group 3

You are in the right track; however, which "formula" are you referring to?

DeleteElaborate.

The gradient of the two points gives us 2 1/3, but the gradient in the equation is 3.

ReplyDeleteWai YanIs the question asking us to compare the line formed by the given points or it's just asking us to check if the points A and B lie on the straight line?

DeleteRead the question again.

We can substitute the points in the equation to find out - Group 1

ReplyDeleteGood!

DeleteHow would the values you find help to draw the conclusion if the points lie on the line or not?

Elaborate further.

Draw the graph after finding the y-intersect and the x-intersect using the y = 3x - 5. Check if the points A (2, -5) and B (5, 2) lie on the straight line.

ReplyDeleteGroup 4

Shanice

DeleteThis is one method if we are given a graph paper to plot and check the points.

What happens, if it's under assessment condition when you do not have the time to do it?

What are some key ideas and understandings you know about the equation of the straight line can help you to determine if the points lie on the line?

replace the values with numbers

ReplyDeletegroup four

You seemed to be on the right track.

DeleteNow, tell us more about what is the "thing" that you are replacing the values.

Elaborate further.

Since it's given the equation of the line, y=3x-5, we could try substituting the X and Y known from the points given, to see if the points lie along the line of that equation.

ReplyDeleteUsing Point A(2,-5)

Eg. If y=3x - 5

y= 3*2-5

y=1

Using B(5,2)

If y=3x-5

y=3*5-5

y=10

Since both don't give us the given Y coordinate, the points don't lie along the line y=3x-5, since it's Y coordinate would be different if its X coordinate remained the same.

Group 1

Absolutely correct!

DeleteWell done, Sophia.

5 points for Group 1

DeleteThe gradient is different hence the points are not on the line (gp3)

ReplyDeleteKeithIs the question asking us to compare the line formed by the given points or it's just asking us to check if the points A and B lie on the straight line?

DeleteRead the question again.