How do you find the axis of symmetry, and the maximum or minimum value of the function $f (x) = - 3 x^{2} + 7 x - 4$ $f(x)= -3x^2+7x-4$ ?

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Answer 1 · 2017-09-22T20:31:24

See the explanation: A sort of cheat approach.

Firstly the coefficient of $x^{2}$ $x^2$ is negative so the graph is of form $⋂$ $nnn$ . Thus we have a maximum.

Write the equation as: $y = - 3 (x^{2} - \frac{7}{3} x) - 4$ $y=-3(x^2color(red)(-7/3)x)-4$

Thus $x_{maximum}$ $x_("maximum")$ is at $x = (- \frac{1}{2}) \times (- \frac{7}{3}) = + \frac{7}{6}$ $x=(-1/2)xx(color(red)(-7/3))=+7/6$

Now it is just a matter of substitution to determine $y_{maximum}$ $y_("maximum")$

Tony B

How do you find the axis of symmetry, and the maximum or minimum value of the function f(x)= -3x^2+7x-4f(x)=−3x2+7x−4f(x)= -3x^2+7x-4?