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# Expressions

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The volume of a cone is given by the formula $$V = \frac{1}{3}Bh$$, where B is the area of the base and h is the height. The area of the base of a cone is 30 square units, and its height is 6.5 units. What is the number of cubic units in its volume?

What is the value of $$1-2x+3x^2-4+5x-6x^2+7-8x+9x^2$$ in terms of x? Express your answer in the form $$ax^2$$+bx+c, where a, b, and c are numbers.

Jul 17, 2020
edited by Unicornrabbit  Jul 17, 2020

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First one, just do the multiplication   (1/3)(30 units2)(6.5 units)  =  65 units3

Second one, just add up like terms:

+3x2     –2x     +1

–6x2     +5x     –4

+9x2     –8x     +7

——–   ––––   –––

Totals          +6x2     –5x     +4    so the answer is 6x2 – 5x + 4

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Jul 17, 2020