U want all the questions replied?
The formula for the distance from a point (x, y, z) to the plane ax +by +cz +d = 0 is this:
.. distance = |ax +by +cz +d|/√(a^2 +b^2 +c^2)
For your point and plane, that is
.. distance = |-8 -2*7 -4*6 -8|/√(1^2 +2^2 +4^2)
.. = 54/√21
.. = (18/7)√21
You haven't shared the list of expressions from which you are to choose an answer.
However: you can perform this estimation yourself as follows:
Round off both -21.87 and 4.79. -21.87 goes to -22 and 4.79 to 5. Then
a good estimate of -21.87 divided by 4.79 would be -22/5, or -4.4.
A negative exponent just means that the base is on the wrong side of the fraction line, so you need to flip the base to the other side. For instance, "x^-2" just means "x2, but underneath, as in 1/x^2.
-4^-2 means the power -2 is only applied to 4 and not the negative sign. -4^-2 = -(4^-2), which is equal to -1/16.
Whereas, (-4)^-2 means the power -2 affects on both negative sign and 4. For example, (-4)^2 is equal to (-4 * -4) which is just 16. Moving on, with (-4)^-2 equals to 1/(-4*-4) = 1/16.
//Hope this helps.
