Find the sum of the even integers from 20 to 50.with solutions please help
1 answer:
Answer: 560
Step-by-step explanation:
There are [20, 22, 24, 26, 28]: 5 even integers for each ten numbers.
The 20's set can be written as 5*20 + (2+4 + 6 + 8) = 5*20 + (20) = 120
The 30's can be written: 5*30 + 20 = 170
40's: 5*40+20 = 220
50's: 5*50+20 = 270
60's: 5*60+20 = 320
Each set is incremented by 50
We want the sets for 20, 30, and 40, plus the number 50.
(120+170+220+50) = 560
You can also do this in Excel (attached). Set the first cell to 20, the next cell below equal to the cell above plus 2. Then draw the second cell down until you've reached 50. Then sum the cells to arrive at 560.
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Reason 4: Isosceles triangle
Reason 5: Segment Addition Postulate
Reason 6: Segment Addition Postulate
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Explanations:
Reason 4: Triangle DCE is an isosceles triangle because of statement 1 of the proof table. The congruent base angles lead to congruent opposite sides.
Reason 5 and 6: This is the idea of breaking any segment into smaller pieces. The smaller pieces glue back together to get the larger original segment.
Reasons 7 and 8: Substitution is a math term which means "replacement". So for instance, in line 7 we started with DB = DC + CB (from line 6), then we replaced the "DB" with "DF" (see line 3); and then replaced "DF" with "DE+EF"
Reason 9: In this step, we subtract DE from both sides to have it go away and cancel out
Reason 10: If two lengths are equal, then the segments are congruent
Reason 11 & 12: Two angles are vertical if they are opposite from one another after forming from two lines crossing. Think of an X shape. Vertical angles are congruent.
Reason 13: We have two pairs of congruent angles, and a pair of congruent sides. The sides are between the angles. The order is important. See the attached image below.
