Abattery was charged. when the charging began, it was 23 percent full. after 30 minutes of charging, the battery was 89 percent full. how fast was the battery charged? percent per minute how long did it take the battery to be fully charged? minutes

Since it started at 23 percent and went to 89 percent, the increase is 66 percent.

Since it took 30 minutes to rise 66 percent, the rate is 2.2 percent per minute.

In order to find how long it will take to charge fully, subtract 23 from 100

100-23=77

77/2.2=35. It should take 35 minutes to charge from 23% to 100%

let's cover over the formula of the vertex:

y = a(x – h)^2 + k

in this formula, (h,k) are the vertex, always remember that the positive or negative value of the vertex is based on the sign it has.

for example, if the vertex is -3,-6 then both the x and y value would have the positive sign attached to it and if it were a positive x and y value, then a negative sign would be attached to it.

with that being said, for our problem the x value is a positive one so we are looking for a number with a negative sign next to it, in this case the first and second choice.

however, for the first answer choice it isn't quite part of the formula so we know that the answer choice correctly displays the x value.

to confirm, we can see if the -1 fits correctly with the second answer choice, and as mentioned above a negative number will have a positive sign attached to it. so, for our problem we can see that -1 has been changed to +1, so we can confirm that the second answer choice is correct.

hence, our final answer is y=(x - 1)^2 + 1