Answer:
xy = -1 and y = -1/x are the same.
They are not linear equations because they are not written in the form
Ax + By = C.
The vertex form of a quadratic function is:
f(x) = a(x - h)² + k
The coordinate (h, k) represents a parabola's vertex.
In order to convert a quadratic function in standard form to the vertex form, we can complete the square.
y = 2x² - 5x + 13
Move the constant, 13, to the other side of the equation by subtracting it from both sides of the equation.
y - 13 = 2x² - 5x
Factor out 2 on the right side of the equation.
y - 13 = 2(x² - 2.5x)
Add (b/2)² to both sides of the equation, but remember that since we factored 2 out on the right side of the equation we have to multiply (b/2)² by 2 again on the left side.
y - 13 + 2(2.5/2)² = 2(x² - 2.5x + (2.5/2)²)
y - 13 + 3.125 = 2(x² - 2.5x + 1.5625)
Add the constants on the left and factor the expression on the right to a perfect square.
y - 9.875 = 2(x - 1.25)²
Now, we need y to be by itself again so add 9.875 back to both sides of the equation to move it back to the right side.
y = 2(x - 1.25)² + 9.875
Vertex: (1.25, 9.875)
Solution: y = 2(x - 1.25)² + 9.875
Or if you prefer fractions
y = 2(x - 5/4)² + 79/8
15 x 25 = 375
15 x 50 = 750
375 + 750 = 1,125
She has 1,125 books.
Answer:
x = 1/5
y = 6
Step-by-step explanation:
System:
{5x + y = 7
{20x + 2 = y
First equation:
5x + y = 7 -> y = -5x + 7
Plug into second equation:
20x + 2 = -5x + 7
Subtract 2 from both sides:
20x = -5x + 5
Add 5x to both sides:
25x = 5
Divde both sides by 25:
x = 5/25 -> 1/5
~~~~~~~~~~~~~~~~~~~~~~~~~~~`
Come back to the first equation:
5x + y = 7
Plus in our x:
5(1/5) + y = 7
Multiply:
1 + y = 7
Subtract 1 from both sides:
y = 6
Hope this helps, have a nice day! :D
