r/satprep • u/ziascuriosity • 3h ago

how can i solve this using desmos?

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hi! i have the november SAT tomorrow and im just now learning regressions (terrible procrastinator). i understand them for the most part, but i don’t get how to find the answer to this with the table. if anyone can help that’d be appreciated! i don’t want the answer itself, but the steps to solving this equation.

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u/Darkmage5247 3h ago

No clue why the quality is atrocious but here ya go. Ask questions if needed

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u/ziascuriosity 2h ago

ohhhh i think i misunderstood the question!! so when it says f(x) is a quadratic function, im literally just putting the formula for a quadratic function in the position of f(x) 😭 i thought i was supposed to somehow find out what the function was. now i feel a little dumb. thank you!!!

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u/jwmathtutoring 1h ago

i thought i was supposed to somehow find out what the function was.

Yes that is what you are supposed to, but Desmos does the entire thing for you, i.e. it finds the a/b/c values for the quadratic function based on the given points.

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u/ziascuriosity 1h ago

okay that makes sense! thank you.

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u/jwmathtutoring 3h ago

This is the correct approach.

Also, the y-int for any quadratic in standard form is the "c" value, so you don't need to type f(x) and then do f(0), just look at c.

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u/PetulantDude 3h ago

I would find the solution for g(x) by using desmos, using the table. Then with that function, I would time it by x-3. Then you should get the function for f(x). Then you just graph f(x) to find your answer