# Posts by black_widow

Total # Posts: 47

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

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

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

Maths
Is it correct?

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 ...

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

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

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

Maths
is it 3?

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

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 ...

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

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) ...

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

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 ...

Algebra

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

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

GEOMetry(TRIANGLE)
AB=50

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)

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

inequality
the range of x is x>4

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

maths
What is Mersenne prime?

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

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

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

maths
still cant solve it.....

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

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

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...

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

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

inequality- why is this wrong?
opps sorry made some calculation mistakes....

inequality- why is this wrong?
it should be x>-3

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

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

biology
Is pore protein = channel protein?

physics

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

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

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

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

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.

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

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

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

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