maths differential equations question
hi, please could I have some help on part a of this question? So i did V=A*rootA because root A will give one side length. Then got dv/da equals 1.5 root A which is wrong. But for the next part I used this and managed to get to the final answer and I'm not sure where I've gone wrong?
question: https://ibb.co/JRsXDnTJ
Thanks!
question: https://ibb.co/JRsXDnTJ
Thanks!
Reply 1
21
Original post
by anonymous56754hi, please could I have some help on part a of this question? So i did V=A*rootA because root A will give one side length. Then got dv/da equals 1.5 root A which is wrong. But for the next part I used this and managed to get to the final answer and I'm not sure where I've gone wrong?
question: https://ibb.co/JRsXDnTJ
Thanks!
question: https://ibb.co/JRsXDnTJ
Thanks!
Thats for one face/square. There are six faces on a cube.
Reply 2
13
Original post
by mqb2766Thats for one face/square. There are six faces on a cube.
But I did the cross sectional area of one side (A) multiplied by the length of one more side which will give volume?
Volume is x^3 I just did x^2( which is area)* x which is root area?
Reply 3
21
Original post
by anonymous56754But I did the cross sectional area of one side (A) multiplied by the length of one more side which will give volume?
Volume is x^3 I just did x^2( which is area)* x which is root area?
Volume is x^3 I just did x^2( which is area)* x which is root area?
For a cube of volume
V = x^3
Then the surface area of the cube is
A = 6 x^2
...
(edited 10 months ago)
Reply 4
13
Original post
by mqb2766For a cube of volume
V = x^3
Then the surface area of the cube is
A = 6 x^2
...
V = x^3
Then the surface area of the cube is
A = 6 x^2
...
doesn't the final answer have to be in terms of A though?
Reply 5
21
Original post
by anonymous56754doesn't the final answer have to be in terms of A though?
Yes, you have two equations and you want to eliminate one variable (x) ...
But its better to be clear and write out the original equations explicitly, then do the (simmple) algebra.
Reply 6
13
Original post
by mqb2766Yes, you have two equations and you want to eliminate one variable (x) ...
But its better to be clear and write out the original equations explicitly, then do the (simmple) algebra.
But its better to be clear and write out the original equations explicitly, then do the (simmple) algebra.
Got it, thank you🙂
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