I:2x – y + z = 7
II:x + 2y – 5z = -1
III:x – y = 6
you can first use III and substitute x or y to eliminate it in I and II (in this case x):
III: x=6+y
-> substitute x in I and II:
I': 2*(6+y)-y+z=7
12+2y-y+z=7
y+z=-5
II':(6+y)+2y-5z=-1
3y+6-5z=-1
3y-5z=-7
then you can subtract II' from 3*I' to eliminate y:
3*I'=3y+3z=-15
3*I'-II':
3y+3z-(3y-5z)=-15-(-7)
8z=-8
z=-1
insert z in II' to calculate y:
3y-5z=-7
3y+5=-7
3y=-12
y=-4
insert y into III to calculate x:
x-(-4)=6
x+4=6
x=2
so the solution is
x=2
y=-4
z=-1
Answer:
15
Step-by-step explanation:
Answer:

80 is the number in the square root
Step-by-step explanation:

Answer:
49
Step-by-step explanation:
Because there is a minus sign infront of x-3, we can convert x-3 into the negative form:
- * x
- * -3
-x + 3
Which gives us:
(-x + 3)(x + 11)
Now expand the brackets with the formula:
(a + b)(c + d) = ac + ad + bc + bd
-x * x = -x²
-x * 11 = -11x
3 * x = 3x
3 * 11 = 33
-x² - 11x + 3x + 33
-x² - 8x + 33
The formula for finding the x coordinate of a vertex in a quadratic equation is:
x = 
Plug known variables in:



Now, to find the y coordinate, plug this variable back into the quadratic equation:
-x² - 8x + 33

y = 49
So the y coordinate of the vertex is 49.
Hope this helps!