14 + 28 + 42 + 56 + … 280
= 14 (1 + 2 + 3 + 4 + … + 20)
= 14 × 20 × 21 / 2
= 2940
where we use the well-known identity,

Answer:
C. X= -2.01 and x= 1.67
Step-by-step explanation:

Y-14=12# x+1 answer of math
Step-by-step explanation:
Option D is the correct answer because we will cross multiply
4/6 = 9/x
4x = 54
X = 27/2
Answer: 4x^2 + 6xy + 2y^2
Step-by-step explanation:
(2x + y)(2x + 2y) =
2x*2x + 2x*2y + y*2x + y^2y =
4x^2 + 4xy + 2xy + 2y^2 =
4x^2 + 6xy + 2y^2