Stupid Algebra Question
Hi,
When you’re simplifying expressions or whatnot, you can’t just divide the expression by the variable because you don’t know that the variable isn’t 0, and anything divided by 0 is non-real.
However, why is it then that you can invariably divide away a variable in the denominator if it also appears on top? E.g. (sinAcosA)/sinA = cosA, because the two sinAs cancel out. But isn’t there a possibility that sinA is 0? 0/0 is still undefined.
Can anyone explain? Thanks.
When you’re simplifying expressions or whatnot, you can’t just divide the expression by the variable because you don’t know that the variable isn’t 0, and anything divided by 0 is non-real.
However, why is it then that you can invariably divide away a variable in the denominator if it also appears on top? E.g. (sinAcosA)/sinA = cosA, because the two sinAs cancel out. But isn’t there a possibility that sinA is 0? 0/0 is still undefined.
Can anyone explain? Thanks.
But youre already told it equals cosA so it's not undefined
Posted from TSR Mobile
Posted from TSR Mobile
I meant if you were just given (sinAcosA)/sinA, you would be able (I’ve seen my teacher do this, so I know) to make it cosA. I just don’t see how you can be sure sinA ≠ 0.
Original post by velocitous
Hi,
When you’re simplifying expressions or whatnot, you can’t just divide the expression by the variable because you don’t know that the variable isn’t 0, and anything divided by 0 is non-real.
When you’re simplifying expressions or whatnot, you can’t just divide the expression by the variable because you don’t know that the variable isn’t 0, and anything divided by 0 is non-real.
"undefined", rather than "non-real"
However, why is it then that you can invariably divide away a variable in the denominator if it also appears on top? E.g. (sinAcosA)/sinA = cosA, because the two sinAs cancel out. But isn’t there a possibility that sinA is 0? 0/0 is still undefined.
Can anyone explain? Thanks.
In this case, an expression like is only defined if in the first place, so it's quite safe to divide away x.
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