9514 1404 393
Answer:
(x, y, z) = (-3, -1, 3)
Step-by-step explanation:
Many graphing calculators can solve matrix equations handily. Here, we use a combination of methods.
Use the last equation to write an expression for z.
z = 4 -x +4y
Substitute this into the second equation:
y -4(4 -x +4y) = -13
y -16 +4x -16y = -13
4x -15y -3 = 0
In genera form, the first equation can be written as ...
3x +y +10 = 0
Now, the solution to these two equations can be found to be ...
x = (-15(10) -1(-3))/(4(1) -3(-15)) = (-150 +3)/(4+45) = -3 . . . using "Cramer's rule"
y = -(10 +3x) = -(10 -9) = -1 . . . . from the first equation
z = 4 -(-3) +4(-1) = 3 . . . . . . . . from our equation for z
The solution to the system is (x, y, z) = (-3, -1, 3).
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<em>Additional comment</em>
Written as an augmented matrix, the system of equations is ...
![\left[\begin{array}{ccc|c}-3&-1&0&10\\0&1&-4&-13\\1&-4&1&4\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D-3%26-1%260%2610%5C%5C0%261%26-4%26-13%5C%5C1%26-4%261%264%5Cend%7Barray%7D%5Cright%5D)
Answer: The answer is 60 square inches.
Step-by-step explanation: Given that Danny has a triangular pyramid where all the four triangles are congruent. The height and base of one triangle are 6 inches and 5 inches respectively. We are to find the surface area of the pyramid.
The area of one triangle is given by

Since the pyramid consists of four congruent triangles, so the surface area of the pyramid will be

Thus, the answer is 60 sq. inches.
If that 25/4 is a fraction them the answer is 53/4. Or in simplest form 3 5/16 or 3.3125