9/7 as a <span>mixed number is 1 2/7</span>
1. The function

is a parabola of the form

. The the formula for the axis of symmetry of a parabola is

. We can infer from our function that

and

, so lets replace those values in our formula:





We can conclude that to the left of the line of symmetry the ball is reaching its maximum height, and to the right of the line of symmetry the ball is falling.
2. Lets check how much time the ball takes to reach its maximum height and return to the ground. To do that we are going to set the height equal to zero:



or


or

From our previous point we know that the ball reaches its maximum time at

, which means that <span>
it takes 1.5 seconds to reach the maximum height and 1.5 seconds to fall back to the ground.</span>
The cost for six pencils would be a total of 150p
The reason why is if three pencils cost 75p and you want to know what the cost of six, since three is half of six you would do this (if 3=75p then 3*2=75p*2 which is 6=150p). As shown, you multiply each side by 2 or double each side