1.The value of (10^8 - 10^2)/(10^7 - 10^3) is closest to which of the following ?
a. 1
b. 10
c. 10^2
d. 10^3
e. 10^4
2.For which of the following functions f is f(x) = f(1-x) for all x ?
a.f(x) = 1-x
b.f(x) = 1-x^2
c.f(x) = x^2 -(1-x)^2
d.f(x) = x^2(1-x)^2
e.f(x) = x/(1-x)
Please provide explanation for your answers .
[spoiler]1. B[spoiler]
[spoiler] 2. D [spoiler][/spoiler]
Some difficult ones .
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ok heres for number 1
(10^8-10^2)=10^2*(10^6-1)
(10^7-10^3)=10^3*(10^4-1)
if you approx 10^6-1 as about 10^6 and 10^4-1 as about 10^4
the equation becomes (10^6)/(10^5)
6-5=1 so its 10^1 or 10
(10^8-10^2)=10^2*(10^6-1)
(10^7-10^3)=10^3*(10^4-1)
if you approx 10^6-1 as about 10^6 and 10^4-1 as about 10^4
the equation becomes (10^6)/(10^5)
6-5=1 so its 10^1 or 10
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if you plug in (1-x) into x^2 you get (1-x)^2 and if you plug it into (1-x)^2 you get (-x)^2 which is the same as (x)^2
if you plug in (x) into x^2 and x into (1-x)^2 you get x^2*(1-x)^2
so with d , you get the same thing if you plug x or 1-x in
answer is d
if you plug in (x) into x^2 and x into (1-x)^2 you get x^2*(1-x)^2
so with d , you get the same thing if you plug x or 1-x in
answer is d
jewbagel wrote:ok heres for number 1
(10^8-10^2)=10^2*(10^6-1)
(10^7-10^3)=10^3*(10^4-1)
if you approx 10^6-1 as about 10^6 and 10^4-1 as about 10^4
the equation becomes (10^6)/(10^5)
6-5=1 so its 10^1 or 10
Could you please explain this:
the equation becomes (10^6)/(10^5)
- rockeyb
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Can you explain this part please .jewbagel wrote:if you plug in (1-x) into x^2 you get (1-x)^2 and if you plug it into (1-x)^2 you get (-x)^2 which is the same as (x)^2
if you plug in (x) into x^2 and x into (1-x)^2 you get x^2*(1-x)^2
so with d , you get the same thing if you plug x or 1-x in
answer is d
- JasLamba
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1.The value of (10^8 - 10^2)/(10^7 - 10^3) is closest to which of the following ?
a. 1
b. 10
c. 10^2
d. 10^3
e. 10^4
For this one we can factor 10^2. So,
Step 1) 10^2(10^6-1)/10^2(10^5 - 10^1)
Step 2) Cancel out the 10^2. This results in: (10^6)-1/(10^5)-10
Step 3) Since this question uses the key word closest, we can deduce that some type of approximation is involved. So basically, it boils down to this: 10^6/10^5 = 10^1
IMO - B
a. 1
b. 10
c. 10^2
d. 10^3
e. 10^4
For this one we can factor 10^2. So,
Step 1) 10^2(10^6-1)/10^2(10^5 - 10^1)
Step 2) Cancel out the 10^2. This results in: (10^6)-1/(10^5)-10
Step 3) Since this question uses the key word closest, we can deduce that some type of approximation is involved. So basically, it boils down to this: 10^6/10^5 = 10^1
IMO - B
- JasLamba
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1.The value of (10^8 - 10^2)/(10^7 - 10^3) is closest to which of the following ?
a. 1
b. 10
c. 10^2
d. 10^3
e. 10^4
For this one we can factor 10^2. So,
Step 1) 10^2(10^6-1)/10^2(10^5 - 10^1)
Step 2) Cancel out the 10^2. This results in: (10^6)-1/(10^5)-10
Step 3) Since this question uses the key word closest, we can deduce that some type of approximation is involved. So basically, it boils down to this: 10^6/10^5 = 10^1
IMO - B
a. 1
b. 10
c. 10^2
d. 10^3
e. 10^4
For this one we can factor 10^2. So,
Step 1) 10^2(10^6-1)/10^2(10^5 - 10^1)
Step 2) Cancel out the 10^2. This results in: (10^6)-1/(10^5)-10
Step 3) Since this question uses the key word closest, we can deduce that some type of approximation is involved. So basically, it boils down to this: 10^6/10^5 = 10^1
IMO - B
when you plug x , or 1-x in for the variable in the original equation, in this case (x), the answer is the same. Hence f(x)=f(1-x)rockeyb wrote:Can you explain this part please .jewbagel wrote:if you plug in (1-x) into x^2 you get (1-x)^2 and if you plug it into (1-x)^2 you get (-x)^2 which is the same as (x)^2
if you plug in (x) into x^2 and x into (1-x)^2 you get x^2*(1-x)^2
so with d , you get the same thing if you plug x or 1-x in
answer is d
- grockit_jake
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For the first question, you dont really need to calculate anything:
(10^8 - 10^2)/(10^7 - 10^3)
Relative to 10^8, 10^2 is very tiny. Think 100,000,000 - 100 = 99,999,900. Not that different from 10^8.
Relative to 10^7, 10^3 is very tiny.
So, in essence, you may think of (10^8 - 10^2)/(10^7 - 10^3) as 10^8/10^7, which equals 10^1 = 10.
(10^8 - 10^2)/(10^7 - 10^3)
Relative to 10^8, 10^2 is very tiny. Think 100,000,000 - 100 = 99,999,900. Not that different from 10^8.
Relative to 10^7, 10^3 is very tiny.
So, in essence, you may think of (10^8 - 10^2)/(10^7 - 10^3) as 10^8/10^7, which equals 10^1 = 10.