# logs help

Watch
Announcements
#1
unsure how to do 2D
I understand how to answer these questions but i get stuck at the first part when making y = to something
0
#2
0
2 years ago
#3
(Original post by justmathshelp)
Use the hint and substitute y = 3^x
0
2 years ago
#4
Have you considered it a hidden quadratic?
0
#5
(Original post by Muttley79)
Use the hint and substitute y = 3^x
with the hint - 3(3^x) i don't understand this? how does this equal 3^x
0
#6
(Original post by Maivnek)
Have you considered it a hidden quadratic?
thats how you solve these questions and i know that my problem is above ^
0
2 years ago
#7
32x + 3x+1 – 10 = 0

32x + 3(3x) – 10 = 0

Make y = 3x

y2 + 3y – 10 = 0

(y+5)(y-2) = 0

y = -5, y = 2

3x = -5 , no solutions

3x = 2 , log 2/log 3
0
2 years ago
#8

Use the log laws to isolate 3^x.
Substitute 3^x for, say, t.
Solve for t.
Plug in 3^x.
Solve for x.

Edit: nevermind ollseph has got full solution
0
#9
(Original post by Maivnek)

Use the log laws to isolate 3^x.
Substitute 3^x for, say, t.
Solve for t.
Plug in 3^x.
Solve for x.

Edit: nevermind ollseph has got full solution

i said before i know the steps my problem is making y = to something and im not asking for the answer just unsure how y = 3^x
0
2 years ago
#10
3^2x = (3^x)^2 according to exponent laws and hint.
3^x+1 = 3*3^x
Now you can substitute
0
2 years ago
#11
Use a chainsaw.
0
#12
(Original post by Maivnek)
3^2x = (3^x)^2 according to exponent laws and hint.
3^x+1 = 3*3^x
Now you can substitute
with 3*3^x

the first 3 has a power to 1 yeah? so thats where the 1 comes from in 3^x+1
0
2 years ago
#13
y is just a placeholder for 3^x and is just an unassigned letter. You're substituting 3^x because you can't deal with the equation in it's complete form, but you know how to deal with a quadratic. And saying 3^x = y creates a quadratic.
0
2 years ago
#14
(Original post by justmathshelp)
with 3*3^x

the first 3 has a power to 1 yeah? so thats where the 1 comes from in 3^x+1
Yes. and an exponent law says: a^(m+n) = a^m * a^n
0
2 years ago
#15
(Original post by ollseph)
....
0
2 years ago
#16
(Original post by justmathshelp)
i said before i know the steps my problem is making y = to something and im not asking for the answer just unsure how y = 3^x
We are trying to 'reveal' the underlying quadratic.

We could use any letter but we just tend to use y.
0
#17
(Original post by Muttley79)
thanks
it was pretty pointless anyway i know how to do these questions i was just unsure what to make y =
0
#18
(Original post by Maivnek)
Yes. and an exponent law says: a^(m+n) = a^m * a^n
yeah thanks x
0
X

new posts Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### Current uni students - are you thinking of dropping out of university?

Yes, I'm seriously considering dropping out (67)
14.69%
I'm not sure (16)
3.51%
No, I'm going to stick it out for now (154)
33.77%
I have already dropped out (8)
1.75%
I'm not a current university student (211)
46.27%