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secondary 3 | A Maths
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secondary 3 chevron_right A Maths chevron_right Singapore

pls explain too :)

ans : x = -(9/8)

Date Posted: 4 years ago
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Heng Hong Hwee
Heng Hong Hwee's answer
15 answers (A Helpful Person)
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The modulus means you make everything inside it positive because you only take into account the magnitude and not the sign. Since x-9 is modded, that means either the original x-9 is already positive or 9-x is positive. Since RHS=LHS, that means 7x must be either equals to x-9 or 9-x. Then just solve the equation. -3/2 is rejected because if x=-3/2, then 7x is negative but 7x cannot be negative because |x-9| (LHS) must be positive so your 7x (RHS) must be positive