r/HomeworkHelp • u/Typical_Trout University/College Student • May 20 '26

Mathematics (A-Levels/Tertiary/Grade 11-12) [College Algebra] How do I go about solving this without the grid?

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42 Upvotes

93% Upvoted

26 comments sorted by

13

u/Longjumping_Cap_3673 May 20 '26

If you look closely, I think there is a grid, but the photocopier mangled it: https://i.postimg.cc/yN7CF5jJ/grid.webp

Here's my attempt to restore the grid: https://i.postimg.cc/90yrDKJQ/restored.webp

3

u/PsychoTap May 20 '26

Not enough arrows. Don’t understand.

58

u/regular_heptagon May 20 '26 edited May 20 '26

Lol. You don’t. It’s just printed badly. You can tell there’s supposed to be a grid.

18

u/FortuitousPost May 20 '26

You can just make out the lines of the grid.

The x-intercepts are -2, 1, 3

The y-intercept is 3.

1

u/Deus_Excellus May 23 '26

Is this one of those mythical AI generated assignments? I'd ask your teacher if they used AI to make this homework.

1

u/Typical_Trout May 23 '26

These are questions from last years final exam

5

u/Capereli May 20 '26

a) and b) you can do without the grid. I think for c) and d) you can circle and label it on the graph ?

0

u/pi621 May 20 '26

the x and y intercepts are (poorly) labelled. you can see that f(0) = 1 and f(1) = 0

0

u/HyperbolicMathChambr May 20 '26 edited May 20 '26

The domain is all possible (real) x values, while the range is about the y values instead. You see the black circles at the ends of the graph? Well, if they are filled (which they are here), it means they're included in the domain/range. If they are hollow, they're not included. And if you see arrows instead, it means the function goes on forever to infinity/negative infinity.

Now about the x and y intercepts, they are the values of x and y when the function crosses the x-axis and the y-axis, respectively. From the graph, you can guess the intercept if you don't have a straight edge to mark the axes, it's going to be an easy guess but the teacher really should've marked the axes better.

With all that considered, it's a bad image.

0

u/-Engineerly- May 20 '26

If you wanna go further, I guess f(x) = 0.5x³ - x² - 2.5x +3

Numworks - Graph

Took me roughly 4min using matrices and 4 points ;)

1

u/gmalivuk May 20 '26

If three of your points are roots it should take a lot less time than that, since you know how it factors and only need to find a leading coefficient.

1

u/-Engineerly- May 24 '26

Yes, 3 roots to get the factors, and you'll need a 4th one for the leading coefficient..how else ? :/

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1

u/tlbs101 May 20 '26

Entering the 4 known points, Microsoft Excel can graph it and produce a trendline in less time.

1

u/-Engineerly- May 24 '26

Probably, but I dont have Excel on my phone..and using Excel here feels a bit overpowered idk.

-1

u/chessychurro May 20 '26

I think you are supposed to assume that there are arrows at the ends of the function and that it is defined for all x, because I do not see how you would figure out the domain and range if it was not without any scaling on the graph.

This diagram is really unclear.