9514 1404 393
Answer:
$2.50
Step-by-step explanation:
The question asks for the total cost of a notebook and pen together. We don't need to find their individual costs in order to answer the question.
Sometimes we get bored solving systems of equations in the usual ways. For this question, let's try this.
The first equation has one more notebook than pens. The second equation has 4 more notebooks than pens. If we subtract 4 times the first equation from the second, we should have equal numbers of notebooks and pens.
(8n +4p) -4(3n +2p) = (16.00) -4(6.50)
-4n -4p = -10.00 . . . . . . . . . . . simplify
n + p = -10.00/-4 = 2.50 . . . . divide by the coefficient of (n+p)
The total cost for one notebook and one pen is $2.50.
__
<em>Additional comment</em>
The first equation has 1 more notebook than 2 (n+p) combinations, telling us that a notebook costs $6.50 -2(2.50) = $1.50. Then the pen is $2.50 -1.50 = $1.00.
One could solve for the costs of a notebook (n) and a pen (p) individually, then add them together to answer the question. We judge that to be more work.
Answer:
3. 294 m²
4. 185,856 mm²
Step-by-step explanation:
To find the surface area of any figure, you can simply find the sum of the areas of all the sides. In question 3, the figure is a triangular prism that has two triangular bases and three rectangular sides. The measurements for the triangles are b = 9m and h = 6m. The formula for the area of a triangle is base times height divided by 2, or 9 x 6 = 54/2 = 27 m². However, since there are two triangular bases, the area for both is 54 m². The measurements for the other three rectangles are given:
7(10) + 8(10) + 9(10) = 240 m² + 54 m² = 294 m²
The surface area of a cube is much easier since all sides are equal and can be found using the formula:
SA = 6s², where 's' represents the measure of a side.
SA = 6(176)² = 185,856 mm²
Sine squared x + cos squared x is equal to 1
Answer:
- Walnuts cost $1.75, chocolate chips cost $2.75
Step-by-step explanation:
<h3>Let the costs be:</h3>
- Walnuts - x
- Chocolate chips - y
<h3>Set equations as per question</h3>
For 7 pounds of walnuts and 9 pounds of chocolate chips, the total cost is $37:
For 5 pounds of walnuts and 3 pounds of chocolate chips, the total cost is $17:
<h3>Solve the system by elimination</h3>
Multiply the second equation by 3 and subtract the first equation, solve for x:
- 3(5x + 3y) - (7x + 9y) = 3(17) - 37
- 15x + 9y - 7x - 9y = 51 - 37
- 8x = 14
- x = 14/8
- x = 1.75
Find the value of y:
- 7*1.75 + 9y = 37
- 12.25 + 9y = 37
- 9y = 37 - 12.25
- 9y = 24.75
- y = 24.75/9
- y = 2.75
now, if we take 2000 to be the 100%, what is 2200? well, 2200 is just 100% + 10%, namely 110%, and if we change that percent format to a decimal, we simply divide it by 100, thus 
.
so, 1.1 is the decimal number we multiply a term to get the next term, namely 1.1 is the common ratio.
![\bf \qquad \qquad \textit{sum of a finite geometric sequence}\\\\S_n=\sum\limits_{i=1}^{n}\ a_1\cdot r^{i-1}\implies S_n=a_1\left( \cfrac{1-r^n}{1-r} \right)\quad \begin{cases}n=n^{th}\ term\\a_1=\textit{first term's value}\\r=\textit{common ratio}\\----------\\a_1=2000\\r=1.1\\n=4\end{cases}\\\\\\S_4=2000\left[ \cfrac{1-(1.1)^4}{1-1.1} \right]\implies S_4=2000\left(\cfrac{-0.4641}{-0.1} \right)\\\\\\S_4=2000(4.641)\implies S_4=9282](https://tex.z-dn.net/?f=%20%5Cbf%20%5Cqquad%20%5Cqquad%20%5Ctextit%7Bsum%20of%20a%20finite%20geometric%20sequence%7D%5C%5C%5C%5CS_n%3D%5Csum%5Climits_%7Bi%3D1%7D%5E%7Bn%7D%5C%20a_1%5Ccdot%20r%5E%7Bi-1%7D%5Cimplies%20S_n%3Da_1%5Cleft%28%20%5Ccfrac%7B1-r%5En%7D%7B1-r%7D%20%5Cright%29%5Cquad%20%5Cbegin%7Bcases%7Dn%3Dn%5E%7Bth%7D%5C%20term%5C%5Ca_1%3D%5Ctextit%7Bfirst%20term%27s%20value%7D%5C%5Cr%3D%5Ctextit%7Bcommon%20ratio%7D%5C%5C----------%5C%5Ca_1%3D2000%5C%5Cr%3D1.1%5C%5Cn%3D4%5Cend%7Bcases%7D%5C%5C%5C%5C%5C%5CS_4%3D2000%5Cleft%5B%20%5Ccfrac%7B1-%281.1%29%5E4%7D%7B1-1.1%7D%20%5Cright%5D%5Cimplies%20S_4%3D2000%5Cleft%28%5Ccfrac%7B-0.4641%7D%7B-0.1%7D%20%20%5Cright%29%5C%5C%5C%5C%5C%5CS_4%3D2000%284.641%29%5Cimplies%20S_4%3D9282%20)
