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# C1 Quadratics help!

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1. I know what to do however all the calculations i've done so far have turned out incorrect,

for A) ive done 144 - 4 (k + 1 ) (k - 4) > =0 however after expanding the brackets for (k + 1) ( k - 4 ) everything goes wrong

help please
2. (Original post by melisss22)

I know what to do however all the calculations i've done so far have turned out incorrect,

for A) ive done 144 - 4 (k + 1 ) (k - 4) > =0 however after expanding the brackets for (k + 1) ( k - 4 ) everything goes wrong

help please
Show your expansion, please.
3. Maybe you're making mistakes with the signs? Eg. forgetting that - - = +?

The other common error that I can think of is that you maybe forgot that the inequality switches when you multiply/divide by -1?

eg: -a >= -3
a <= 3
4. (Original post by RDKGames)
Show your expansion, please.
144 - 4 ( k^2 - 4k + k - 4 )

then i did 144 - 4k ^ 2 + 16k - 4k + 16 > = 0
5. (Original post by surina16)
Maybe you're making mistakes with the signs? Eg. forgetting that - - = +?
aaaaa i dont think i did ???
6. (Original post by melisss22)
144 - 4 ( k^2 - 4k + k - 4 )

then i did 144 - 4k ^ 2 + 16k - 4k + 16 > = 0
That's good. What's wrong with it then??
7. (Original post by melisss22)
144 - 4 ( k^2 - 4k + k - 4 )

then i did 144 - 4k ^ 2 + 16k - 4k + 16 > = 0
I'd recommend dividing everything by 4 outside of the brackets in the first step shown here before you do anything. It should help you get to the right solution easier.
8. (Original post by melisss22)
144 - 4 ( k^2 - 4k + k - 4 )

then i did 144 - 4k ^ 2 + 16k - 4k + 16 > = 0
144 - 4k ^ 2 + 16k - 4k + 16 > = 0

160 - 4k ^ 2 + 12k > = 0

4k^2 -12k -160 =0
Divide everything by 4 then
9. (Original post by RDKGames)
That's good. What's wrong with it then??
oh my god im so stupid igjdosidjfs i just realised i've been simplifying the it wrong the whole time
10. (Original post by melisss22)
oh my god im so stupid igjdosidjfs i just realised i've been simplifying the it wrong the whole time
Rookie mistake.
11. (Original post by Ayaz789)
144 - 4k ^ 2 + 16k - 4k + 16 > = 0

160 - 4k ^ 2 + 12k > = 0

4k^2 -12k -160 =0
Divide everything by 4 then
i realised i divided 160 / 4 wrong the whole time D: thank you
12. (Original post by melisss22)
oh my god im so stupid igjdosidjfs i just realised i've been simplifying the it wrong the whole time
How have you done it wrongg? ^
13. (Original post by melisss22)
i realised i divided 160 / 4 wrong the whole time D: thank you
Ahh okay np

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