A) The first step needs 100 bricks, the second needs 98, the third needs 96, and so on. Therefore the number of bricks for the nth step is: a_n = a_1 + d(n-1), where a_1 = 100 (the first term), d = -2 (difference).
a_n = 100 - 2(n-1) = 102 - 2n, and for the 30th step, a_30 = 102 - 2*30 = 42. So the top step will need 42 bricks.
b) The total staircase will need: 100 + 98 + 96 + ... + 44 + 42, and there are n = 30 terms. Using the formula for the sum of an arithmetic sequence:
S = (a_1 + a_n)*n/2 = (100 + 42)*30/2 = 2130
Therefore, 2130 bricks are required to build the entire staircase.
Answer:
A store is offering a 14% discount on all items. Write an equation relating the sale price S for an item to its list price L.
Step-by-step explanation:
Answer:

Step-by-step explanation:



Answer:
Third
Step-by-step explanation:
First would be, simplified, 2x+10=2x-10
Second, simplified, -2x-10=2x-10
Third, simplified, -2x-10=-2x-10
Fourth, simplified, -2x+10=2x-10
So it's third :)
hope this helps :D
Answer:
y + 7 = -
(x - 1)
Step-by-step explanation:
The equation of a line in point- slope form is
y - b = m(x - a)
Where m is the slope and (a, b) a point on the line
Here m = -
and (a, b) = (1, - 7), thus
y - (- 7) = -
(x - 1), that is
y + 7 = -
(x - 1) ← in point- slope form