i got these marked wrong on my homework because i am a dumbie.?

Question

i hate math!!!!! can you show me how to do this correctly?

the sum of a number and its reciprocal is 10/3. what is the number?

i have 1/3, 3 written down and a buncha scribbled stuff, i skipped this problem to come back to it, and i dont know how to get started again. can you please show HOW you checked your answer?

and how do you simplify 10^-4 and a^-3b^2

for those, i got 1/10,000 and 5/3^3.

for 3x^-2, i put 1/3x^2.

haha those are horrible answers, i am SO LOST! =(

Answer 1

I am sorry to tell you that i dont know how to solve it but i too am a maths hater.It feels good to find someone similar

Answer 2

You're not a dumbie.

For the first question - I won't repeat what someone else has already explained - you got the answers right. It was most likely marked wrong because you didn't show enough working. To check the answer you try both numbers in your initial equation (you'll notice that one if the reciprocal of the other so basically you just add the two together and you see than 3 +1/3 = 10/3)

1/10,000 isn't wrong but I think your teacher want you to keep it as 1/10^4

Is the equation meant to be (a^-3)(b^2). I don't know how you got 5/3^3. But if I've understood correctly - the simplified version is b^2/a^3

As for the last one. Unless 3x was in brackets so (3x)^-2 then the power only replies to x so it would 3/x^2.

But you're on the right track for most of them. You certainly not a dumbie.

Answer 3

I think I got the first one (the sum of a number and its reciprocal is 10/3. what is the number?)

Let the number be x
so its reciprocal is 1/x

so x+1/x =10/3
x2 + 1/x =10/3 (the 2 stands for squared)

3x2 + 3 = 10x

3x2-10x+3=0 (now thats a quadratic equation..you find the roots)

3x2-9x-x+3 =0
3x(x-3)-1(x-3)=0
(3x-1)(x-3) =0

so the no. is either 3 or 1/3

Answer 4

Lynne's got your first one right.

You aren't wrong - 10^(-4) is 1/10,000. By "simplify", they probably meant to write it as 1/10^4.

I'm not sure where you got 5/3^3, as you haven't given values for a and b. To simplify it as it stands, you'd have to write (b^2)/(a^3).

For the last one, the "-2" power only applies to the x, not to the 3. So 3x^-2 = 3/(x^2).

Edit: Oh, and by the way, hon - you aren't a dummie. But I suppose you already know that. :)