Answer:
25150
Step-by-step explanation:
First, we have to see that this is an arithmetic sequence... since to get the next element we add 5 to it. (a geometric sequence would be a multiplication, not an addition)
So, we have a, the first term (a = 4), and we have the difference between each term (d = 5), and we want to find the SUM of the first 100 terms.
To do this without spending hours writing them down, we can use this formula:

If we plug in our values, we have:

S = 50 * (8 + 495) = 50 * 503 = 25150
x= -13 , y=11
Step-by-step explanation:
Using elimination method, make the x variable equal to eliminate the variable
-3x - y = -28
2x+ 3y=7
2(-3x-y =28)
3(2x+3y=7)
-6x - 2y =56
6x +9y=21
Apply addition
7y = 77
y=77/7 = 11
Use the value of y=11 in
2x+ 3y=7
2x +3(11) =7
2x +33 =7
2x=7-33
2x= -26
x= -26/2 = -13
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Solving simultaneous equations :brainly.com/question/12318095
Keywords ; linear combination method,equations, justify,steps
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2x+38=180
2x=142 (or x+x=142 from which 2x=142)
x=71
The unknown angles are each 71
You know this answer is logical as, since two sides are 21 it hints that we are looking at an equilateral triangle, which means two of its angles will be the same
916=900
791=90
The difference is 10.