Answer:
- 494
Step-by-step explanation:
Breaking down the summation into it;s component parts
= 4k -
k(k + 1) ← substitute k = 19
= (4 × 19 ) - 1.5 × (19 × 20)
= 76 - (1.5 × 380)
= 76 - 570
= 494
Answer: 
Step-by-step explanation:

Answer:
Hi! I hope this is correct please inform me if this is incorrect :)
a = 1 will have.
2a + 3 < 9 - 3a.
2a + 3 > 10 -3a.
3a - 2a + 1>2.
a = 2 will have
ANY others I did not include in a = 1 :)
Please once again tell me if this is incorrect.
Step-by-step explanation:
Answer:
10) x=9
11) x=25
Step-by-step explanation:
a triangle is 180º total
10) 2x+8x+90=180
10x=90
x=9
11) 3x+1+2x+2+2x+2=180
7x+5=180
7x=175
x=25