Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

You are not logged in.

- Topics: Active | Unanswered

**Zeeshan 01****Member**- Registered: 2016-07-22
- Posts: 648

Q1. x=25(a^2) -25(b^2) and Y=[5(a-b)]^2 then

A. X=Y

B. X<Y

C. X>Y

D. None

Q2.. if a+b=3(c+d) which of the following is average of a,b,c,d

A. c+d

B.(c+d)\4

C. 3(c+d)\8

D. 3(c+d)\4

Q3.. if 7x+3y=17 and 3x+7y=19 , WHat is arithmetic mean of x and y???

A. 1.55

B. 1.8

C. 3.6

D. 36

Q.4 when a>b then (a^3)-(b^3) is greater than

A. zero

B.. (a+b)^3

C. (a-b)^3

D. none

Q5.. Rule to Add two scalar is Head to TAil rule or right hand rule or simple addition"??

MZk

Offline

**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,322

hi

Q1. D is not a possible answer as one of the other three must be true.

I tried this:

Now subtract:

If a = b then X = Y

If b>0 and b>a then 50b(b-a) > 0 then Y > X etc etc

So the answer seems to depend on the values of a and b.

Should answer D read "It is not possible to decide."

Q2. Try simplifying (a+b+c+d)/4

Q3. You could try solving for x and y, but a quicker method is to add the equations and re-arrange to find (x+y)/2

Q4. I think this also depends on the values of a and b. I need to spend more time on it so I'll come back to this question later.

LATER EDIT:

You can make a deduction from this if you know more about a and b such as a, b > 0 and b>a

Did you get told this at the start of these questions? It's important to have the whole question.

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

**Zeeshan 01****Member**- Registered: 2016-07-22
- Posts: 648

Plz decide only one option in question 1 I also know that option d is incorrect

Suppose if option d is

D. Not sure then ans d is correct

*Last edited by Zeeshan 01 (2017-07-17 22:08:52)*

MZk

Offline

**iamaditya****Member**- From: Planet Mars
- Registered: 2016-11-15
- Posts: 766

You can also try one more formula for

It isPractice makes a man perfect.

There is no substitute to hard work

All of us do not have equal talents but everybody has equal oppurtunities to build their talents.-APJ Abdul Kalam

Offline

**Zeeshan 01****Member**- Registered: 2016-07-22
- Posts: 648

Hehe I know all these formulas

MZk

Offline

**Zeeshan 01****Member**- Registered: 2016-07-22
- Posts: 648

bob wrote:

Q1. D is not a possible answer as one of the other three must be true.

I tried this:Now subtract:

Why u subtract???

MZk

Offline

**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,322

A. X=Y

B. X<Y

C. X>Y

If you calculate Y - X and the answer is:

zero ............. means Y = X

positive .........means Y > X

negative ........means X > Y

So subtracting was a quick way to help decide between the alternatives.

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

**Zeeshan 01****Member**- Registered: 2016-07-22
- Posts: 648

??

MZk

Offline

**Zeeshan 01****Member**- Registered: 2016-07-22
- Posts: 648

Arithmetic mean formula is A=(x+y)\2

MZk

Offline

**Zeeshan 01****Member**- Registered: 2016-07-22
- Posts: 648

Can you Clearify Question 2,3,4???

MZk

Offline

**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,322

Q2. The average is (a + b + c + d)/4

If you start with this and use the given information to eliminate a and b it is a short work to get one of the possible answers.

Q3. Add the equations together : 10x + 10y = 36

It is a short step to get (x+y)/2

Q4. Depending on what values I choose for a and b I get many possible answers:

If a=1.1 and b=1, then answers A and C are TRUE.

If a=-2 and b=-3, then answers A,B and C are all TRUE.

If a=1 and b=0, then answer A is TRUE.

I'll leave it to you to try to find a case where only D is TRUE.

Bob

Children are not defined by school ...........The Fonz

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

Offline

**Zeeshan 01****Member**- Registered: 2016-07-22
- Posts: 648

Okk!,, it takes long time

MZk

Offline