(d): y = mx+n
m = -2/3 ⇒ y = (-2/3)x +n
A(-4, 6) ∈ d ⇒ 6 = (-2/3)·(-4) +n ⇒ 6 = 8/3 +n ⇒
⇒ n = 6 - 8/3 ⇒ n = 10/3
Now, we have:
y = (-2/3)x +10/3
Let S be the sum,
S = 2 + 4 + 6 + ... + 2 (n - 2) + 2 (n - 1) + 2n
Reverse the order of terms:
S = 2n + 2 (n - 1) + 2 (n - 2) + ... + 6 + 4 + 2
Add up terms in the same positions, so that twice the sum is
2S = (2n + 2) + (2n + 2) + (2n + 2) + ... + (2n + 2)
or
2S = n (2n + 2)
Divide both sides by 2 to solve for S :
S = n (n + 1)
Answer:
A,C, F
Step-by-step explanation:
y> 7 so,
eliminating B,D and E
now, for A, 2×1 < 9
for C, 2×-1<10
for F, 2× 17< 59
