Q. g(x)=(5−2x)(14+2x)The function g is defined by the given equation. For what value of x does g(x) reach its maximum?
Identify Function Type: Identify the type of function.The function g(x)=(5−2x)(14+2x) is a quadratic function because it can be written in the form ax2+bx+c after expanding the product.
Expand to Find Coefficients: Expand the function to find the coefficients.Expanding the product, we get:g(x)=(5)(14)+(5)(2x)−(2x)(14)−(2x)(2x)g(x)=70+10x−28x−4x2g(x)=−4x2−18x+70
Write in Standard Form: Write the function in standard quadratic form.The standard form of a quadratic function is ax2+bx+c. From Step 2, we have:g(x)=−4x2−18x+70Here, a=−4, b=−18, and c=70.
Determine Maximum X-Value: Determine the x-value at which the maximum occurs.For a quadratic function in standard form ax2+bx+c, the x-value of the vertex, which gives the maximum (if a < 0) or minimum (if a > 0) value, is given by −b/(2a).Here, a=−4 and b=−18, so:x=−(−18)/(2×−4)x=18/−8x=−9/4
Verify Maximum: Verify that this x-value gives a maximum.Since the coefficient a=−4 is negative, the parabola opens downwards, and the vertex represents the maximum point of the function.
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