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secondary 3 | A Maths
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Dee
Dee

secondary 3 chevron_right A Maths chevron_right Singapore

Please help me with this question. Thank you

Date Posted: 1 year ago
Views: 358

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Smith
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3 answers (A Helpful Person)
1st
Using quadratic formula
Dee
Dee
1 year ago
Thank you very much
Boy Mow Chau
Boy Mow Chau
1 year ago
squaring both sides is correct method to remove the square root, but squaring both sides may result in "extraneous" solutions which do not satisfy the original equation. so after finding the possible values of x, it is necessary to substitute each value back into original equation to check that the original equation is satisfied.

for this question, on the left-hand side, sqrt[2x] refers only to the positive root. when x = (6+sqrt[11])/25 is substituted into the equation, LHS = +0.8633..., but RHS = -0.8633, so this value of x has to be rejected.

x = (6-sqrt[11])/25 is the only valid answer.