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The given equation relates the variables [tex]$x$[/tex] and [tex]$y$[/tex]. For what value of [tex][tex]$x$[/tex][/tex] does the value of [tex]$y$[/tex] reach its minimum?

[tex]y = x^2 - 14x + 22[/tex]


Sagot :

To determine the value of [tex]\( x \)[/tex] at which [tex]\( y \)[/tex] reaches its minimum for the quadratic equation [tex]\( y = x^2 - 14x + 22 \)[/tex], we can follow these steps:

1. Identify the Standard Form:
The given quadratic equation is in the form [tex]\( y = ax^2 + bx + c \)[/tex], where [tex]\( a = 1 \)[/tex], [tex]\( b = -14 \)[/tex], and [tex]\( c = 22 \)[/tex].

2. Formula for the Vertex's x-coordinate:
The x-coordinate of the vertex of a parabola given by the quadratic equation can be found using the formula:
[tex]\[ x_{\text{vertex}} = -\frac{b}{2a} \][/tex]
This formula gives the x-coordinate at which the minimum (or maximum) value of [tex]\( y \)[/tex] occurs for a parabola that opens upwards (or downwards).

3. Substitute the Values of [tex]\( a \)[/tex] and [tex]\( b \)[/tex]:
[tex]\[ x_{\text{vertex}} = -\frac{-14}{2 \cdot 1} = \frac{14}{2} = 7 \][/tex]

4. Verify by Calculating the Minimum Value [tex]\( y \)[/tex]:
To find the minimum value of [tex]\( y \)[/tex], substitute [tex]\( x = 7 \)[/tex] back into the original equation:
[tex]\[ y_{\text{minimum}} = (7)^2 - 14 \cdot 7 + 22 = 49 - 98 + 22 = -27 \][/tex]

The minimum value of [tex]\( y \)[/tex] is [tex]\(-27\)[/tex] at [tex]\( x = 7 \)[/tex].

Therefore, [tex]\( y \)[/tex] reaches its minimum value when [tex]\( x = 7 \)[/tex].