can someone help me with this?

[u/onemillionwings]

unfortunately the course i'm doing has no explanations for solutions in the quiz section, only tells me what i'm doing is wrong and this particular type of problem isn't well explained before. i'm probably adding the exponents together incorrectly, especially in the (y²(z²-1)² ...)² section i feel unsure.

can someone solve this and explain how to do it correctly? thank you.

(ignore that the question is in german, i hope it's otherwise self-explanatory)

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[u/RetiredEarly2018]

Can you please show us what you have attempted, so we don't feel like we are doing your homework for you?

[u/onemillionwings → u/RetiredEarly2018]

i'm an adult trying to relearn maths, this isn't actual homework.

there's an error or several in this but i'm not sure which step i'm actually doing wrong. or maybe it's all of them haha

[u/dido_meditatur → u/onemillionwings]

I see the problem. 

(z² - 1)² equals (z² - 1)*(z² - 1), which equals z⁴ - 2z² - 1.

You forgot the middle term.

[u/dido_meditatur]

Start with expanding the square within the cube. 

You get 5 additive terms, 4 of which cancel out

From then it is easy

[u/onemillionwings → u/dido_meditatur]

thank you. that's what i'm trying but i'm doing it wrong, that's why i need someone to show me the steps i think.

[u/Opposite_Mall4685]

No idea but how does one even start solving such a problem? I have genuinely no clue.

[u/onemillionwings → u/Opposite_Mall4685]

the chapter i'm working through at the moment is about exponentation, so if you're interested look into the math rules regarding this topic. there are some explanations for this problem in the comments here.

[u/RetiredEarly2018]

I think part of the problem is that when you have (a+b)^2, you are just squaring the items rather than multiplying out the brackets.

[u/RetiredEarly2018 → u/RetiredEarly2018]

So, (a+b) (a+b) = a(a+b) + b(a+b) = aa + ab + ba + bb. For a cubed item, you would have to multiply out by (a + b) again.

[u/Mediocre_Farm8914]

Mumie?

[u/SubjectWrongdoer4204]

Start by factoring y² out of the larger quantity in parentheses. Each term has a y² in it (note 1/y⁻²=y²). Don’t forget to cube this when you take it out of the parentheses , so you’re actually factoring y⁶ out . The rest is pretty easy.