Answer: If perpendicular lines intersect, then they form right angles.
Step-by-step explanation:
You take the first part, "perpendicular lines intersect", and add the "if" to it. Then, you take the second part, "to form right angles", and add the "then" in front of it to get your answer, "If perpendicular lines intersect, then they form right angles."
Hope it helps! :)
Answer:
The first our to the second hour
To solve this we are going to use the formula for speed:

where

is the speed

is the distance

is the time
Let

be the speed of the boat in the lake,

the speed of the boat in the river,

the time of the boat in the lake, and

the time of the boat in the river.
We know for our problem that <span>the current of the river is 2 km/hour, so the speed of the boat in the river will be the speed of the boat in the lake minus 2km/hour:
</span>

We also know that in the lake the boat<span> sailed for 1 hour longer than it sailed in the river, so:
</span>

<span>
Now, we can set up our equations.
Speed of the boat traveling in the river:
</span>

But we know that

, so:

equation (1)
Speed of the boat traveling in the lake:

But we know that

, so:

equation (2)
Solving for

in equation (1):


equation (3)
Solving for

in equation (2):




equation (4)
Replacing equation (4) in equation (3):


Solving for

:






or

We can conclude that the speed of the boat traveling in the lake was either
6 km/hour or
5 km/hour.
I think this is right maybe
Answer:
Step-by-step explanation:
No idea what a gouilleul Sequence is, but hopefully it will help to show how I would find the answer.
A geometric sequence means a term is multiplied by something over and over So say we start with 100 and the common ratio is .5 then the sequence would go 100,50,25,12.5,6.25 and so on. Another way of writing it is:
100*.5^0 = 100
100*5^1 = 50
100*.5^2 = 100*.25 = 25
and so on.
ANyway, here we have the first and fourth term. so that's 3.5*x^0 and 3.5*x^3. Keep in mind the exponent will be n-1 when the term you want to find is the nth term. Anyway, we know 3.5*x^3 = 28, so we just use algebra to find x, which is the common ratio.
3.5*x^3 = 28
x^3 = 8
x = 2
So the common ratio is 2, or in other words it keeps doubling. You could try it real quick, keep doubling the starting term 3.5
3.5, 7, 14, 28 and 28 is the fourth term.
So we know the common ratio. you could just add the four terms listed then for part b, but there is an equation, for in case they ask you to find the sum of say the first 100 terms. that wouldn't be fun. Anyway, the formula is a((1-r^n)/(1-r)) where a is the starting term, r is the common ratio and n is the number term. In your case that's 3.5((1-2^4)/(1-2)) = 52.5. You can actually check since it's only 4 terms. 3.5 + 7 + 14 + 28 = 52.5.
If you want to know how that formula was gotten let em know and I can explain or give a link to a video or something to show.