# Posts by black_widow

Total # Posts: 47

**chemistry**

How to compare the melting point of two ionic bod or two covalent bond?

*April 28, 2013*

**chemistry**

why does MgO has a higher boiling and melting point than NaCl?

*April 28, 2013*

**Math ( Polynomial )**

by using long division, divide x^4-6x^3+16x^2-25x+10with x^2-2x+k, then you will find: remainder=(-9+2k)x +10-8k+k^2 comparing with x + a, -9+2k=1,k=5 a=10-8k+k^2,a=-5 therefore k + a=5-5=0

*April 13, 2013*

**Maths**

Is it correct?

*April 12, 2013*

**Maths**

My way of solving...... Let k=m+1 2^(m+1)-2^m <1000 2^m <1000 m<=9 therefore k<=10 For distinct value of k and m, when k=1, m=0 when k=2, m=0,1 when k=3, m=0,1,2 . . . when k=10 2^k−2^m<1000 2^10-2^m<1000 m>=4 no of possible value of m is 5 total ...

*April 12, 2013*

**chemistry**

is this mean that e/z notation can definitely explain cis-trans isomerism but cis-trans not necessary can explain e/z notation ?

*April 12, 2013*

**chemistry**

i have seen it but still don't understand.....

*April 12, 2013*

**chemistry**

What is the difference between e/z notation and cis-trans isomerism?

*April 12, 2013*

**Maths**

is it 3?

*April 12, 2013*

**Math**

sorry about that.... I thought 0 is neither even nor odd....

*April 6, 2013*

**Math**

Let a>b a=2n+1+2k ,n,k is positive b=2n+1 (a+b)/2=2n+1+k (a-b)/2=k If k is odd, then (a+b)/2 is even (a-b)/2 is odd If k is even, (a+b)/2 is odd (a-b)/2 is even The same method also applies if a<b (However I assume that a,b are distinct number because if a=b, (a-b)/2=0 ...

*April 6, 2013*

**algebra**

let x^(1/3)=a 6a^2-11a+4=0 a=0.5, a=4/3 x=1/8, x=64/27

*April 1, 2013*

**maths**

My answer is 440 My way of solving: xyz(z)=−64y−128x (1) xyz(x)=−32y−32z (2) 3xyz(y)=128x−64z (3) (1)-(2) xyz(z-2x)=64(z-2x) xyz=64 ,z=2x if z=2x,x=y=z=0 if xyz=64, sub xyz=64 into (1),(2),(3) simplify it and you can get: z=-y-2x (4) 2x=-y-z (5) ...

*April 1, 2013*

**Algebra**

f(x)=3x^2-21x+36 sum of roots =-(-21/3)=7

*March 26, 2013*

**Algebra**

sorry the answer should be 101 I do like this: first consider the possible last digit of the number, then you have 0,1,5,6 Let N be ab For number end with 0, the last two digits of N will be 00 no numbers can be formed as 00 is not a 2 digit numbers For number end with 1, it ...

*March 26, 2013*

**Algebra**

the answer is 76

*March 26, 2013*

**Collage Physics**

The pull of cable is 5.24x10^3N The force exerted by the man =75N Is it correct?

*March 26, 2013*

**GEOMetry(TRIANGLE)**

Let length of AB =a sABC=sABD+sACD (s stands for area) 1/2x60x(a^2-30^2)^0.5=1/2x(16a+32a) 5(a^2-30^2)^0.5=4a 25a^2-16a^2=25x30^2 a^2=2500 a=50

*March 25, 2013*

**GEOMetry(TRIANGLE)**

AB=50

*March 25, 2013*

**Using the remainder**

Given f(x)=2x^3-10x^2+11x+12 f(3)=2(3)^3-10(3)^2+11(3)+12 = 9 because f(3)not equal to 0 Therefore x-3 is not a factor of f(x)

*March 24, 2013*

**Solve the inequality**

x^2(8+x)(x-9)/(x+4)(x-7) >=0 x^2(8+x)(x-9)(x+4)(x-7)>=0 therefore the ranges are x>=9,0<=x<=7,-8<=x<=-4 But x cannot equal -4 or 7 therefore the ranges of x are x>=9,0<=x<7,-8<=x<-4

*March 24, 2013*

**inequality**

the range of x is x>4

*March 24, 2013*

**Math (Number Theory)**

1/a + 1/b + 1/c = 0 bc+ac+ab = 0 a^2 + b^2 + c^2 =(a+b+c)^2 -2(ab+bc+ac) =(11)^2-2(0) =121

*March 24, 2013*

**maths**

What is Mersenne prime?

*March 24, 2013*

**maths**

Solve the inequality //(2x-1)(x+3)/-4/< 1 where /x/ is the modulus of x.

*March 24, 2013*

**maths**

Is every Fermat number 2^(2^n) + 1 composite for n > 4?

*March 23, 2013*

**University of Ghana**

Average speed = (26+14+15+17)/2 km/h =36 km/h =36x1000/(60x60) m/s =10 m/s

*March 23, 2013*

**maths**

still cant solve it.....

*March 23, 2013*

**maths**

Solve the inequality //(2x-1)(x+3)/-4/< 1 where /x/ is the modulus of x.

*March 23, 2013*

**maths**

If G is a group of order 12, the G must have a subgroup of all of the following orders EXCEPT Choose one answer. a. 0 b. 12 c. 2 d. 3 e. 6 f. 4

*March 23, 2013*

**maths**

Let the bottom edge of a rectangular mirror on a vertical wall be parallel to and h feet above the level floor. If a person with eyes t feet above the floor is standing direct at a distance d feet from the mirror, what is the relationship among h,d and t if the person can just...

*March 23, 2013*

**maths**

What is the value of e^i(pi)? where i^2 =-1 ,e =exponential

*March 22, 2013*

**maths**

Prove : (a^2+b^2+c^2+d^2)(1/a^2+1/b^2+1/c^2+1/d^2)greater equal to 16

*March 21, 2013*

**inequality- why is this wrong?**

opps sorry made some calculation mistakes....

*March 21, 2013*

**inequality- why is this wrong?**

it should be x>-3

*March 21, 2013*

**maths**

Prove : (a^2+b^2+c^2+d^2)(1/a^2+1/b^2+1/c^2+1/d^2)greater equal to 16

*March 17, 2013*

**maths**

Given that a,b,c >0 Prove : (a/b + b/c +c/a)(b/a +c/b +a/c)>0

*March 17, 2013*

**biology**

Is pore protein = channel protein?

*March 17, 2013*

**physics**

Is the answer is 170m/s?

*March 16, 2013*

**physics**

Impulse = change in momentum I= m(v-u) I=70.5 (5.85-0) I=412.4Ns

*March 16, 2013*

**Physics**

Consider only vertical component (because the object does not move horizontally) Use formula v=u+at v=0+9.8(7) v=68.6m/s

*March 16, 2013*

**Calculas**

is it x^3 -(2x+5)/(x+4) ?

*March 16, 2013*

**Calculas**

Is your question is f(x)= x^3-2x+(5/x)+4 ?

*March 16, 2013*

**Physics**

Yes the magnitude will be the same until the force exceed the maximum frictional force then the system will only move with an acceleration.

*March 16, 2013*

**Physics**

Let the magnitude of friction force = f acceleration ,a = 0 (because it moves with constant speed) F=ma 20-f=30x0 f=20N

*March 16, 2013*

**physics**

Let the resistive force = f F=ma 10-f=0.2x2 f=9.6N

*March 16, 2013*

**math**

Let 25x^2+(a−15)x+9=0 Discriminant B^2-4AC=0 (only one distinct root) (a-15)^2-4(25)(9)=0 (a-15)^2=900 a=15+30 or a=15-30 a=45 a=-15 therefore sum of a =45+(-15) a =30

*March 15, 2013*

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