Answer: 25x^2 - 1^2
Explanation:
(5x+1) (5x-1)
(5x)^2 - 1^2
25x^2 - 1^2
9-5=4 Therefore f=4
Hope this helps
Answer:
x = -5
Step-by-step explanation:
Since these two triangles are similar, the ratio between the corresponding lengths of each triangle will be the same.
This means the ratio between one side of each triangle (e.g. AD and DC) will be the same as the ratio between a different side of each triangle (e.g. BE and BC).
So, to create an equation for the sides which contain the unknown 'x', we must first find the ratio between the two sides by using a different set of sides.
On the right side we are given 9 for AD, and 18 for DC.
9/18 = 0.5
This means that the extra length of the larger triangle from the smaller one (AD) is half the length of the smaller triangle (DC). We can use this to make an equation for x:
If AD/DC = 0.5, then BE/EC will also = 0.5
BE = x+23
EC = x+41
Therefore:

Now we can solve by multiplying both sides by x+41 to eliminate the fraction:

Now we multiply out the brackets and move the terms to different sides:



And if we substitute the -5 into the equations:
-5+23 = 18
-5 + 41 = 36
We will see that -5 does indeed give us the same ratio between the lengths:
18/36 = 0.5
Hope this helped!
Answer:
Charlie should use a stopwatch with minutes and seconds
Step-by-step explanation:
charlie should not count in his head as it is not accurate, he could count too fast or slow
Charlie should not look at that clock and the seconds will affect the 25 minutes, whether it be less or more
Charlie should not use an hourglass as he might flip it over too soon or quick and it's not very accurate
therefore using the stopwatch allows him to accurately and fairly keep track of the exact time