Hello :
all n in N ; n(n+1)(n+2) = 3a a in N or : <span>≡ 0 (mod 3)
1 ) n </span><span>≡ 0 ( mod 3)...(1)
n+1 </span>≡ 1 ( mod 3)...(2)
n+2 ≡ 2 ( mod 3)...(3)
by (1), (2), (3) : n(n+1)(n+2) ≡ 0×1×2 ( mod 3) : ≡ 0 (mod 3)
2) n ≡ 1 ( mod 3)...(1)
n+1 ≡ 2 ( mod 3)...(2)
n+2 ≡ 3 ( mod 3)...(3)
by (1), (2), (3) : n(n+1)(n+2) ≡ 1×2 × 3 ( mod 3) : ≡ 0 (mod 3) , 6≡ 0 (mod)
3) n ≡ 2 ( mod 3)...(1)
n+1 ≡ 3 ( mod 3)...(2)
n+2 ≡ 4 ( mod 3)...(3)
by (1), (2), (3) : n(n+1)(n+2) ≡ 2×3 × 4 ( mod 3) : ≡ 0 (mod 3) , 24≡ 0 (mod3)

Step-by-step explanation:

st + 3t = 6 for s
Subtract 3t to both sides
st + 3t - 3t = 6 - 3t
Simplify
st = 6 - 3t
Divide both sides by t
st/t = (6-3t)/3
simplify
s = 6/3 - 3t/3
s = 2 - t
Answer:

General Formulas and Concepts:
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
<u>Algebra I</u>
- Coordinates (x, y)
- Midpoint Formula:

Step-by-step explanation:
<u>Step 1: Define</u>
Point (2, 9)
Point (8, 1)
<u>Step 2: Identify</u>
(2, 9) → x₁ = 2, y₁ = 9
(8, 1) → x₂ = 8, y₂ = 1
<u>Step 3: Find Midpoint</u>
Simply plug in your coordinates into the midpoint formula to find midpoint
- Substitute in points [Midpoint Formula]:

- [Fractions] Add:

- [Fractions] Divide:

Answer:
3/10
Step-by-step explanation:
4/15+x=17/30
x=17/30-4/15
x=17/30-8/30
x=9/30
simplify
x=3/10