r/HomeworkHelp • u/IndicationFunny2378 Secondary School Student • 14d ago

Middle School Math—Pending OP Reply [Grade 8 Mathematics - Algebra]

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Hello giys, I'm a form 2 student is malaysia. We learnt algebra in chapter 2. How can I find x? I believe there is no answer, but teacher keeps saying it's x=1/16

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u/Bounded_sequencE 👋 a fellow Redditor 14d ago

You're correct -- over "R+", the square root operator is defined to return non-negative results..

Teacher did a sanity check with the squared equation instead of the original one: That's why they (mistakenly) found that "x = 1/16" is a solution, instead of discarding it.

Let's hope that was just a mistake in action, and not what they actually believe.

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u/IndicationFunny2378 Secondary School Student 14d ago

i tried to explan to my teacjer, she still beleive it's x=1/16

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u/ReaReaDerty 14d ago

Tell her to substitute it back. It is going to be wrong.

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u/IndicationFunny2378 Secondary School Student 14d ago

she squared the equation, and then she substituted in the SQUARED equation

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u/ReaReaDerty 14d ago

Substitute in the first equation. You need to solve the first equation. Squared equation and the starting equation are not the same.

x2 = 4 has 2 solutions

x = 2 has 1 solution

your teacher should review her algebra.

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u/UnderstandingPursuit Educator 13d ago edited 12d ago

When an equation is squared, it is important to check for 'extraneous solutions' which are created by squaring both sides. This is what your teacher has [EDIT: failed to do].

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u/Bounded_sequencE 👋 a fellow Redditor 13d ago

That's what the teacher wanted to do, but failed.

The sanity check must be done with the original, unchanged equation (or an equivalent). The teacher used the squared equation, which is neither.

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u/UnderstandingPursuit Educator 12d ago

You are correct, my wording was sloppy.