Answer:
B)blocks in 5th row=15+(5-1)(-2)
Step-by-step explanation:
We are given that
Number of block in bottom row=15
Each row has 2 fewer blocks than the previous row
We have to find the formula would you use to find the number of blocks in the 5th row.
Number of blocks in second row=15-2=
Number of blocks in third row=15-2-2=
Number of blocks in 4th row=
Number of blocks in 5th row=
Therefore, number of block in 5th row
This is required formula to find the number of blocks in the 5th row
Hence, option B is true.
B)blocks in 5th row=15+(5-1)(-2)
Answer: 41
Step-by-step explanation:
9*(-2)*(-2) - 4*(-2) - 3 = 9*4 + 8 - 3 = 36 + 5 = 41
Ok, I'm going to start off saying there is probably an easier way of doing this that's right in front of my face, but I can't see it so I'm going to use Heron's formula, which is A=√[s(s-a)(s-b)(s-c)] where A is the area, s is the semiperimeter (half of the perimeter), and a, b, and c are the side lengths.
Substitute the known values into the formula:
x√10=√{[(x+x+1+2x-1)/2][({x+x+1+2x-1}/2)-x][({x+x+1+2x-1}/2)-(x+1)][({x+x+1+2x-1}/2)-(2x-1)]}
Simplify:
<span>x√10=√{[4x/2][(4x/2)-x][(4x/2)-(x+1)][(4x/2)-(2x-1)]}</span>
<span>x√10=√[2x(2x-x)(2x-x-1)(2x-2x+1)]</span>
<span>x√10=√[2x(x)(x-1)(1)]</span>
<span>x√10=√[2x²(x-1)]</span>
<span>x√10=√(2x³-2x²)</span>
<span>10x²=2x³-2x²</span>
<span>2x³-12x²=0</span>
<span>2x²(x-6)=0</span>
<span>2x²=0 or x-6=0</span>
<span>x=0 or x=6</span>
<span>Therefore, x=6 (you can't have a length of 0).</span>
