Tell me if i'm right, 10 points on the line

Explanation:

x^2+8x+7 factors to (x+1)(x+7)

x^2+4x-21 factors to (x-3)(x+7)

Therefore, the numerator (x^2+8x+7)(x-3) updates to (x+1)(x+7)(x-3)

The denominator (x^2+4x-21)(x+1) updates to (x-3)(x+7)(x+1)

We have three pairs of terms that will cancel between the numerator and denominator. The (x+1) terms pair up and cancel out, so do the (x+7) terms and also the (x-3) terms as well. Everything cancels out. The only thing left is 1 because x/x = 1 where x is nonzero. We can have a more complicated expression replace x to get the same basic idea. This is what I mean by "canceling".

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.