Answer:
D
Step-by-step explanation:
im just guessing sorry if its wronh
You can make a start by putting together an expression for the sum of the even integers between 1 and k inclusive.
Let S be the sum of the even integers between 1 and k inclusive.
Then:
<span><span>S=2+4+6+⋯+(k−2)+k</span></span>
As k is even, you can say r = 2k and so:
<span><span>S=2(1+2+3+⋯+(r−1)+r)</span></span>
<span>Now the sum of the first </span><span>r</span><span> numbers is well-known, it's the </span><span>r</span>th triangle number and we have:
<span><span>1+2+3+⋯+(r−1)+r=<span><span>r(r+1)/</span>2</span></span></span>
<span>Now we can keep it simple and say </span><span><span>2k=4r </span></span><span>and so:</span>
<span><span>S=2(1+2+3+⋯+(r−1)+r)=4r=2<span><span>r(r+1)</span>2</span>=r(r+1)</span></span>
<span>So you can build a quadratic in </span><span>r</span><span> and so get </span><span>k.</span>
Answer:
63
Step-by-step explanation:
15 dolls-
15 x 3 = 45 stuffed animals
45+18 = 63
Step-by-step explanation:
products of

Hope it will help :)
As per the problem
A jet flew for 2 hrs before strong head winds reduced its speed by 40 mph.
It took the plane 5 hrs to travel 1,380 miles
Total time=5 hrs, Time of fly before headwinds
,
Time of fly in headwinds
Let the speed before head winds 
Then speed in headwinds
As we know that

Hence using this formula and the given data we can write

Hence speed before flying into the headwinds=300mph