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Exam Hack | CIE A2 Maths | P3 | Absolute Value/Inequality Question

🕑 Added 2021-03-03 04:23:27 +0000 UTC

Comments

Neha Karia

I don't understand when you square an equation and when you don't, cause this qn, |2x+1| + |2x-1| >5, I was trying to square both the sides and work but it won't work, then I realised that the answer is gotten without the square.

Intuitive

√((22a)^2 - 4(15)(-5a^2)) = √((484a^2) + (300a^2)) = √((784a^2)) = 28a

Siddarth Arora

Hello Mr Jacob. I had an issue with Q8 on the worksheet. I got the quadratic equation x = ( (22a)±√((22a)^2 - 4(15)(-5a^2)) ) / ( 2 (15) ). However I don't understand how you managed to get it simplified to (22a ± 28a) / 30. How did you manage to simplify the whole square root to 28a? Would appreciate it a lot if you could help me out. Thanks.

KAVIN P00931

he is the goat!

Oriana Mas Grimon

I can’t download the worksheets 😭

Ayub

Hi I just wanted to ask where is the content on dividing polynomials since it was a part of the same chapter as absolute values and inequalities

Intuitive

It doesn't matter but I would say always use ln(x). As log base e is very useful and used alot in other areas of engineering, science and mathematics. :)

Niyati Kumaran

hey , for the last question , do we take log or lan on both sides to find x. does it matter which one we take?

Intuitive

All good, ask as many questions as you want. I prioritise people on here so I’ll answer pretty fast usually :)

Jessica Zziwa

Thank you, I get it now

Intuitive

Or in English Minus one 2^x minus another 2^x is minus two 2^x ‘s

Intuitive

Awesome glad it’s helping you :)

Intuitive

(2^x -1)(2^x-1) = (2^x)(2^x) - (2^x) - (2^x) + 1 Which gives (2^2x) -2(2^x) + 1 Another way to think about it is if you make u = 2^x then the equation is: (u - 1)^2 = u^2 - 2u + 1 Then as u = 2^x this becomes: (2^x)^2 - 2(2^x) + 1

Jessica Zziwa

I do have one question. In Q2, when you expanded (2^x-1)^2, you got -2(2^x) for (-2^x-2^x), I don't really get how that works

Jessica Zziwa

Hi. I just joined and the worksheets are helping already. Thank you!

Intuitive

Thanks for replying! For you as a teacher Luisana I think this content will be best given to students a couple months before their exams. (As it’s heavily exam focused rather than content focused) Hope everything is going well with your classes :)

Luisana Guaita

Hi Jacob! I have downloaded the material, but we started classes, and it's been crazy. I'll check it during the weekend for feedback, but you always nail it anyway!