Answer:
n = 10
Step-by-step explanation:
The sum to n terms of an arithmetic sequence is
= 
[ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
Here a₁ = 12 and d = 5 and = 345, thus
[ (2 × 12) + 5(n - 1) ] = 345 ( multiply both sides by 2 )
n( 24 + 5n - 5) = 690 ← distribute and simplify left side
n(19 + 5n) = 690
19n + 5n² = 690 ( subtract 690 from both sides )
5n² + 19n - 690 = 0 ← in standard form
(5n + 69)(n - 10) = 0 ← in factored form
Equate each factor to zero and solve for n
5n + 69 = 0 ⇒ 5n = - 69 ⇒ n = - 
n - 10 = 0 ⇒ n = 10
However, n > 0 , thus n = 10
Answer:
72
Step-by-step explanation:
2(8) + 7(8)
16 + 56
72
Answer:
8x^6
Step-by-step explanation:
Since all sides of a cube are congruent, the area of one face of the cube can be found using the area formula of a square. A= length x width
Since all sides are the same, you can fill in your formula as:
6x6
Multiply and you get
6 x 6= 36
Then, make sure you use the proper units for area and your final answer is
36 in^2
Answer:
180
Step-by-step explanation:
C + D = 180 degrees since they are a linear pair
D = 127 degrees, so
C + 127 = 180
to get the C, you need to subtract 180 degrees bt 127 degrees
180 - 127 = C
