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How do you write the quadratic in vertex form given #y= -3x^2 + 21x#?

Answer 1

#y = -3(x - 7/2)^2+147/4 = -3(x - 3.5)^2+36.75#

#y = -3x^2+21x = -3(x^2-7x)# #= -3((x-(7/2))^2 - (7/2)^2)# #= -3(x-(7/2))^2+3(7/2)^2# #= -3(x - 7/2)^2+147/4# #= -3(x - 3.5)^2+36.75#

The vertex of the parabola is #(3.5, 36.75)#

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Answer 2

Julia Adams

To write the quadratic in vertex form given ( y = -3x^2 + 21x ), you complete the square. The vertex form is ( y = a(x - h)^2 + k ), where ( (h, k) ) is the vertex. First, factor out the common factor from the terms involving ( x ). Then, complete the square by halving the coefficient of ( x ), squaring it, and adding and subtracting it inside the parentheses. Finally, simplify the expression.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.