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solniwko [45]
3 years ago
8

Find the exponential function that passes through the points (1, 3) and (2, 9). A) y = 12x B) y = 9x C) y = 6x D) y = 3x

Mathematics
2 answers:
Dmitriy789 [7]3 years ago
7 0

Answer:

D

Step-by-step explanation:

An exponential function which crosses through (1,3) and (2,9) will have a base of 3 since the y values are multiples of 3.

3^1 = 3

3^2 = 9

This means that the function is y = 3^x.

Irina18 [472]3 years ago
3 0

y = 3x

Substitute the two points into the equation y = abx, giving 3 = ab1 and 9 = ab2.

Since a = a, then  

3

b1

=  

9

b2

, rearranged yields 3b2 = 9b1 → 3b2 − 9b = 0 → b(3b − 9) = 0

Thus, b = 0 or b = 3.

A curve of exponential function never drop below the x-axis, ignore any values of b that are less than or equal to zero.

Therefore, insert b = 3 into  

3

b1

= a and  

9

b2

= a → a = 1 for both equations.

y = abx

y = (1)(3x)

y = 3x

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Answer:

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Step-by-step explanation:

We must remember that a parabola is represented by a quadratic function, which can be formed by knowing three different points. A quadratic function is standard form is represented by:

y = a\cdot x^{2}+b\cdot x + c

Where:

x - Independent variable, dimensionless.

y - Dependent variable, dimensionless.

a, b, c - Coefficients, dimensionless.

If we know that (3, -30), (-2, 0) and (18, 0) are part of the parabola, the following linear system of equations is formed:

9\cdot a +3\cdot b + c = -30

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324\cdot a +18\cdot b + c = 0

This system can be solved both by algebraic means (substitution, elimination, equalization, determinant) and by numerical methods. The solution of the linear system is:

a = \frac{2}{5}, b = -\frac{32}{5}, c = -\frac{72}{5}.

The equation of the parabola is y = \frac{2}{5}\cdot x^{2}-\frac{32}{5}\cdot x -\frac{72}{5}.

Now, we calculate the average rate of change (r), dimensionless, between x = -2 and x = 8 by using the formula of secant line slope:

r = \frac{y(8)-y(-2)}{8-(-2)}

r = \frac{y(8)-y(-2)}{10}

x = -2

y = \frac{2}{5}\cdot (-2)^{2}-\frac{32}{5}\cdot (-2)-\frac{72}{5}

y(-2) = 0

x = 8

y = \frac{2}{5}\cdot (8)^{2}-\frac{32}{5}\cdot (8)-\frac{72}{5}

y(8) = -40

r = \frac{-40-0}{10}

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The average rate of change of the parabola is -4.

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Step-by-step explanation:

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Answer:

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Step-by-step explanation:

The given binomial expression is:

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When we compare to:

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We have

a =  {x}^{2}

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The nth term is given by;

T_{r+1}=^nC_ra^{n-r}b^r

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We substitute into the formula to get:

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