Here is a picture of a sample pyramid:
Source: http://www.mathwarehouse.com/solid-geometry/pyramid/images/volume-of-pyamid-problem-1.jpg
To find the volume of any pyramid, use this formula:
\(V=\frac{1}{3}Bh\)
Let V = Volume of pyramid
Let B = Area of the base
Let h = Perpendicular height from the base to the common vertex
Using the picture above, let's find the volume of the above pyramid. The first thing we must find is B, the area of the base. In the example above, the base is a rectangle, so let's find B.
\(B =10*8\)
\(B=80\)
Ok, now the height is 6, as given in the diagram. Let's plug all the values in.
\(V=\frac{1}{3}*80*6\) | With multiplication, you can do the calculation in any order you'd like because of the commutative property of multiplication. For ease of calculation, ill do \(\frac{1}{3}*6=2\) |
\(V=80*2\) | |
\(V=160in^3\) | Remember to leave units in your final answers, and be sure to leave it as a cubed unit! |
Here's another method to solve this problem:
Not all authorities agree on the standard form of a line; some believe it to be \(Ax+By=C\) and others believe it to be \(y=mx+b\). However, for the purposes of this problem, I will utilize the first form, \(Ax+By=C\).
For a system, however, we have this form:
1. \(A_1x+B_1y=C_1\)
2. \(A_2x+B_2y=C_2\)
Let's convert both equations into that form:
1. \(y=\frac{1}{3}x-2\)
\(y=\frac{1}{3}x-2\) | Subtract y to both sides |
\(\frac{1}{3}x-2-y=0\) | Add 2 to both sides |
\(\frac{1}{3}x-y=2\) | |
2. \(-2x+6y=18\)
Luckily for us, this equation is already in its desired form, so we can move on.
Ok, let's look at the equations side by side again:
1. \(\frac{1}{3}x-y=2\)
2. \(-2x+6y=18\)
Now, look at the ratio of the coefficients. If \(\frac{A_1}{A_2}=\frac{B_1}{B_2}\neq\frac{C_1}{C_2}\), then the system has no solution. If \(\frac{A_1}{A_2}=\frac{B_1}{B_2}=\frac{C_1}{C_2}\), then the system has infinitely many solutions. If \(\frac{A_1}{A_2}\neq\frac{B_1}{B_2}\), then there is exactly one solution.
Let's try to see if this works.
Let's check to see if \(\frac{\frac{1}{3}}{-2}=\frac{-1}{6}\neq\frac{2}{18}\)
First, let's simplify \(\frac{\frac{1}{3}}{-2}\)
\(\frac{\frac{1}{3}}{-2}\) | Apply the rule that \(\frac{\frac{a}{b}}{c}=\frac{a}{b*c}\) |
\(\frac{1}{3*-2}\) | |
\(\frac{1}{-6}\) | |
\(\frac{-1}{6}\) | |
Ok, let's check the condition again: Does \(\frac{-1}{6}=\frac{-1}{6}\neq\frac{2}{18}\)? Yes, 2/18 simplifies to 1/9, which is not equal to -1/6.
As I stated above, when a system of equations has the relationship of \(\frac{A_1}{A_2}=\frac{B_1}{B_2}\neq\frac{C_1}{C_2}\) then there is no solution. Therefore, this system has no solution. If there is no solution to this system, then the lines must be parallel because otherwise the lines would intersect and would have a solution.
Despite all of this work that I have shown, Hecticlar's method appears to be easier to follow and is probably more efficient because this method cannot tell if the lines are perpendicular...
To solve for x, you must use the square root and remember to split the answers into 2:
\((x+3)^2=7\) | Take the square root of both sides |
\(x+3=\sqrt{7}\) | However, remember that the absolute value equation splits your answer into the negative and positive answer |
\(x+3=\pm\sqrt{7}\) | Subtract 3 on both sides |
\(x=\pm\sqrt{7}-3\) | |
\(x\approx-0.35425\hspace{1mm}\text{and}\hspace{1mm}x\approx-5.64575\) | Here are your answers rounded, but you want to keep your answer as it is above because that is the exact value. |
To solve for x and y, first solve for a variable and plug it into the other equation. Since you specified solving by substitution, I'll use that method. Here are your 2 equations:
1. \(2x+4y=-32\)
2. \(-3x+y=6\)
I'll solve for y in the second equation because it has a coefficient of 1.
\(-3x+y=6\) | To isolate y, add 3x to both sides. |
\(y=6+3x\) | |
Now that I have solved for y in one equation, substitute y in the other.
\(2x+4y=-32\) | In the previous calculation, we deduced that y=6+3x, so replace y. |
\(2x+4(6+3x)=-32\) | Distribute the 4 into the parentheses to ease the simplification process. |
\(2x+24+12x=-32\) | Combine the like terms, specifically 2x and 12x. |
\(14x+24=-32\) | Subtract 24 on both sides. |
\(14x=-56\) | Divide by 14 on both sides to isolate x. |
\(x=-4\) | |
Plug x into an equation and solve for y. I'll plug it into equation 2
\(-3x+y=6\) | Substitute the calculated value for x, -4. |
\(-3(-4)+y=6\) | Simplify -3*-4. |
\(12+y=6\) | Subtract 12 on both sides |
\(y=-6\) | |
Therefore, the solution set is (-4,-6)
In this equation, our goal is to isolate the unknown, x. Let's see how we would go about doing that
\(3(2-x)=5(2x-7)+2\) | This is the original equation. Distribute the 3 and the 5 into the given parentheses. |
\(6-3x=10x-35+2\) | Combine -35+2. |
\(6-3x=10x-33\) | Add 33 to both sides, |
\(39-3x=10x\) | Add 3x to both sides. |
\(39=13x\) | Divide by 13 to isolate x. |
\(3=x\) | |
There ya go!