Answer:
42-38
42 + (-38)
-38+42
Step-by-step explanation:
In all of these expressions, the 38 has to be negative because that is what you're taking away from the 48. When you have -(- it turns into a +.
In -42 + 38 the 42 is negative, but that is Emma's total amount so it's positive
With -42 -(-38) they did the just added those two together which would make the 42 still negative and the 38 positive.
THen with 42 + 38 the 38 is being subtracted from what she has so you would not add 38 to her total.
Answer:
76 m²
Step-by-step explanation:
The figure has been decomposed into 3 rectangles as shown in the attachment. Therefore:
Area of the figure = area of rectangle 1 + area of rectangle 2 + area of rectangle 3
✔️Area of rectangle 1:
Area = L*W
L = 2 m
W = 4 m
Area = 2*4 = 8 m²
✔️Area of rectangle 2:
Area = L*W
L = 4 m
W = 6 - 4 = 2 m
Area = 4*2 = 8 m²
✔️Area of rectangle 3:
Area = L*W
L = 10 m
W = 6 m
Area = 10*6 = 60 m²
✅Area of the figure = 8 + 8 + 60
= 76 m²
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>
