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If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)

The length of a rectangle plus its width is 25 cm. the area is 156 square cm. what are the length and width of the rectangle? separate the answers with a comma.

What effect would doubling all the dimensions of a triangular pyramid have on the volume of the pyramid? explain your reasoning.