Common Algebra Mistake

[Jack-hdov]

This is interesting because it shows that you should be careful with unknowns, the assumption that y ≠ 0 and consequent divide by y lead to a partially incorrect solution.

[elbr]

Gotta appreciate a man who uses a chalk board. Top tier

[miorgel]

You can't divide by a variable unless you assume it isn't zero, as to not divide by zero.
So every time you divide by a variable you need to remember the possibility it's a zero

[hamhead]

This is how I explain to my wife why I don't want to go to her sisters house.

[yogeshbl]

A simple thing to remember is there are always n solutions for a number in an equation whose power is n. For example y2 = 1 has 2 solutions, 1 and -1. Y3 = 27 has 3 solutions, one is 3 and the other two are imaginary, (-3+3i)/2 and (-3-3i)/2

[Sciencedoneright]

To people who think the professor is being too rigorous: I have had countless experiences where there was no solution except 0 and lost marks due to that, and also this thing is important in writing the solution anytime

[meguillozebern]

Here is one tip for you guys, If the equation has a squared term then, first you must make the equation look like this-- _a_x^2 + _b_x = 0 where a and b are constants. then factor it.

Always remember that this kind of equation has two possible answers.

[tk]

I watch your math solving equation right before bed, it’s relaxing and I’m learning at the same time 🙏💯

[yeskay]

It’s a quadratic equation (with a square) - hence 2 possible answers

[SigmaSixSoftware]

This is why most math textbooks will make you equate the problem to zero by “sending everything to the left hand side”

[achiever]

Brilliantly illustrated sir love from India.

[aguywithwhiskers]

Changes it to simple quadratic equation 👌👌

[The_Koolaid_Control]

This is why i factor before solving. It helps me personnally to break a problem down better and have less of a problem in these situations.

[codewithkam]

As a rule of thumb we have squared variable in the equation so we should expect two answers.

[commirevo]

I encounter similar misconceptions with my 8th graders regarding linear equations. When given an equation like 4x = 5x they often incorrectly assume there are no solutions (because the equation x + 4 = x + 5 would have no solution and they are generalizing that pattern to all operations). So many people forget that the product of zero and anything is zero.

[kdeee]

"If the equation has no constant, then one of the solutions is zero."

[dfdxdfdydfdz]

When you divide by something, you need to make sure it isn’t 0.

[Ziumbaa]

theres a formula we use in school (swedish, so it might look different in other countries) that goes:
x^2 + px + q = 0
x = -(p/2) ± √((p/2)^2 - q)

to use it in this case would be to go subtract 3y from both sides to get y^2 - 3y = 0, that means that in the formula, p = -3 and q = 0, so we can just add it, and its
y = -(-3/2) ± √((-3/2)^2 - 0)
y = 1.5 ± √(1.5^2)
y = 1.5 ± 1.5
y1 = 3
y2 = 0
pretty simple actually, also if you dont understand why there are 2 answers, its because if a negative number squared is.a positive number, so in almost any situation, if a problem includes an unknown number squared, there are 2 possible answers

[MeemeeChern]

Wish I had a teacher like you when I was learning math.

[cyborggaming]

In India, it’s a 9th standard algebra question where you have to find the zeros of the polynomials