The straight line L1 has equation x+2y=4 The straight line L2 passes through the points (-1,-7) and (7,9) Michael says that the lines L1 and L2 are perpendicular Is Michael correct and you must show your working out clearly

Yes

Step-by-step explanation:

The idea is to use the formula for perpendicular gradients,

meaning m1 * m2 = -1

Since L2 passes through 2 points and to find gradient we just need 2 points,

we can use the 2 given points given

L2 gradient is (9 - (-7)) / (7 - (-1)) = 16/8 = 2

x + 2y = 4 rewrite as  y = -(0.5)x + 2

so our m1 is -0.5 and m2 is 2

-0.5 * 2 = -1  which was what we wanted to show.

L1 and L2 are perpendicular

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.