Topic : Number-Square Root
1.
2.
from: category_eng

1.Modification
How will u eliminate the square root?

Ans: B

2.Mathematical Writing
1/2 sqrt (x) = 2x.
1/2 sqrt (x) = 2x.
sqrt (x) = 4x.
x= 16x^2
1/16 =x

Ans: A

1.
How can u modify it to add those terms? Can u add sqrt(2)+sqrt(3)?
2.
(sqrt a)^2=a
3.

4.

5.
We need an relationship between n and n^2 We need an relationship between n and sqrt(n)
6.
Mixed Topics
Do you know the most important formula in GMAT math? \[(a - b)(a + b) = {a^2} - {b^2}\]
7.

8.

9.
could be!!! n > 25^2.. Answer shoulbe be greater than 25.
10.
let's eliminate the square root.
11.

12.
To find x, we need to make an equation.
1. A
Modification
How can u modify it to add those terms? Can u add sqrt(2)+sqrt(3)?
sqrt(80)+sqrt(125) = 4sqrt(5)+5sqrt(5)
2. C
Calculation
(sqrt a)^2=a
4*7=?
3. A
4. d
5. B
Understanding
We need an relationship between n and n^2 We need an relationship between n and sqrt(n)
sqrt(n^2) =|n|
sqrt(n)^2 = n

(1)it's not sufficient.
(2)It's sufficient because square of integer is also integer.
6. a
Modification
Do you know the most important formula in GMAT math? \[(a - b)(a + b) = {a^2} - {b^2}\]
(2-1)(3-1)=2
7. E
8. D
9. 26
could be!!! n > 25^2.. Answer shoulbe be greater than 25.
10. c
Modification
let's eliminate the square root.
49
(1) it's not enough itself.
(2) it's not enough itself.
If we combine those, then 50
11. a
12. E
Mathematical Writing
To find x, we need to make an equation.
3+ 4/sqrt(5-x) =6
sqrt(5-x)= 4/3
5-x= 16/9
9*(5-x)=16 <- Can u guess the answer at this stage without cal?
45 -9x=16
29=9x
x=3.2