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final pratice exam help please no calculator

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asked Dec 10, 2014 in PRECALCULUS by Baruchqa Pupil

3 Answers

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21)

General form of conic section Ax2 + Cy2 + Dx + Ey + F = 0

Conics can be classified according to the coefficients (x2 and y2) of the equation.

If the coefficients of  x2 and y2 Are of the same sign but unequal coefficients, then the graph will be an ellipse.

If both coefficients of x2 and y2 Are of the same sign with unequal coefficients then the graph will be circle.

If coefficients are of opposite sign, then it will be a hyperbola.

A parabola results when there is an " x2 " but no " y2 " (or) a " y2 "  but no "x2 ".

In the options, there is one equation having " x2 " but no " y2 ".

Therefore, x2 - 2x + 3y = 1 graph represents a parabola in the xy - plane.

Option (b) is correct.

answered Dec 10, 2014 by david Expert
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22) The function f(x) = x2 + 3

To f(x + h), substitute (x + h) for x in f(x) = x2 + 3 .

f(x +  h) = (x + h)2 + 3

f(x +  h) = x2 + h2 + 2xh + 3

[f(x + h) - f(x)]/h = [(x2 + h2 + 2xh + 3) - (x2 + 3)]/h

= (x2 + h2 + 2xh + 3 - x2 - 3)/h

= (h2 + 2xh)/h

= h(h + 2x)/h

= h + 2x

[f(x + h) - f(x)]/h = 2x + h

Option (c) is correct.

answered Dec 10, 2014 by david Expert
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23) The function  f(x)= 3x4  - 4x3  + 5

y = 3x4  - 4x3  + 5

Differentiating with respect to x.

y' = 12x - 12x2

Here y' is slope of the tangent line.

Slope of the horizontal line is zero.So equate first derivative = 0

12x3  - 12x2  = 0

12x2(x - 1) = 0

Apply zero product property.

12x2 = 0 and x - 1 = 0

x = 0 and x = 1

Using the x - value find the corresponding y - value with the curve.

y = 3(0)4 - 4(0) + 5 = 5

The point ( 0, 5)

For x = 1,

y = 3(1) - 4(1) + 5

= 3 - 4 + 5 = 4

The horizontal tangent points are (0, 5) and (1, 4).

Option (a) is correct.

answered Dec 10, 2014 by david Expert

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