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Answer No 14

9514 1404 393

  21x² +20x +100 = 0

Step-by-step explanation:

We know the sum of the roots of x² +bx +c = 0 is -b, and their product is c. If the roots are α and β, then ...

The sum of the roots of the new equation will be ...

  -b' = (α+1/β)+(β+1/α) = (α+β) +(1/α +1/β) = (α+β)(1 +1/(αβ))

The product of the roots of the new equation will be ...

  c' = (α+1/β)(β+1/α) = αβ +2 +1/(αβ)

Using the above relations for (α+β) and αβ, we find that ...

  -b' = (-b)(1 +1/c)

  c' = c + 2 + 1/c

For the given equation, our definition of b and c is ...

  b = 2/3

  c = 7/3

so the new equation has values ...

  b' = (2/3)(1 + 1/(7/3) = (2/3)(10/7) = 20/21

  c' = 7/3 + 2 + 1/(7/3) = 13/3 + 3/7 = 100/21

So, the equation with the roots of interest is ...

  x² +20/21x +100/21 = 0

Multiplying by 21 gives ...

  21x² +20x +100 = 0

the answer is: d) o, f, and kr.

atomic radius of bromine (br) is 114 pm.

atomic radius of oxygen (o) is 73 pm.

atomic radius of fluorine (f) is 72 pm.

atomic radius of krypron (kr) is 112 pm.

the atomic radius of a chemical element is a measure of the size of its atom.

the atomic radius varies with increasing atomic number, but usually increases because of increasing of number of electrons.

the atomic radius decreases across the periods because an increasing number of protons, because greater attraction between the protons and electrons.

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