If v varies partly as aq and partly as q square when v=34,q=2 and v=190

,q=5find vwhen q=10

1 answer

To find the relationship between \( v \) and \( q \), we start with the concept that \( v \) varies partly as \( aq \) and partly as \( q^2 \). This can be expressed mathematically as:

\[ v = k_1 \cdot aq + k_2 \cdot q^2 \]

where \( k_1 \) and \( k_2 \) are constants that we need to determine.

Step 1: Set up equations from given values

From the information you provided, we have two scenarios:

  1. When \( v = 34 \) and \( q = 2 \): \[ 34 = k_1 \cdot a \cdot 2 + k_2 \cdot 2^2 \] \[ 34 = 2a k_1 + 4k_2 \]

  2. When \( v = 190 \) and \( q = 5 \): \[ 190 = k_1 \cdot a \cdot 5 + k_2 \cdot 5^2 \] \[ 190 = 5a k_1 + 25k_2 \]

Step 2: Write the system of equations

We now have a system of equations:

  1. \( 2a k_1 + 4k_2 = 34 \) \quad (1)
  2. \( 5a k_1 + 25k_2 = 190 \) \quad (2)

Step 3: Solve the system of equations

We can manipulate equation (1) and (2) to solve for \( k_1 \) and \( k_2 \).

From equation (1), we can express \( k_2 \) in terms of \( a \) and \( k_1 \):

\[ k_2 = \frac{34 - 2ak_1}{4} \]

Substituting \( k_2 \) into equation (2):

\[ 5ak_1 + 25\left(\frac{34 - 2ak_1}{4}\right) = 190 \]

Multiply through by 4 to eliminate the fraction:

\[ 20ak_1 + 25(34 - 2ak_1) = 760 \]

Expanding this gives:

\[ 20ak_1 + 850 - 50ak_1 = 760 \]

Combining the terms:

\[ -30ak_1 + 850 = 760 \]

Rearranging yields:

\[ -30ak_1 = 760 - 850 \]

\[ -30ak_1 = -90 \]

\[ 30ak_1 = 90 \]

\[ ak_1 = 3 \quad \Rightarrow \quad k_1 = \frac{3}{a} \]

Step 4: Substitute \( k_1 \) back to find \( k_2 \)

Substitute \( k_1 \) back into equation (1):

\[ 2a\left(\frac{3}{a}\right) + 4k_2 = 34 \]

\[ 6 + 4k_2 = 34 \]

\[ 4k_2 = 28 \]

\[ k_2 = 7 \]

Step 5: Final equation for \( v \)

Now substitute \( k_1 \) and \( k_2 \) back into the original equation:

\[ v = \frac{3}{a} \cdot aq + 7q^2 \]

\[ v = 3 + 7q^2 \]

Step 6: Find \( v \) when \( q = 10 \)

Now we substitute \( q = 10 \) into our final equation:

\[ v = 3 + 7(10^2) \]

\[ v = 3 + 7 \cdot 100 \]

\[ v = 3 + 700 \]

\[ v = 703 \]

Thus, the value of \( v \) when \( q = 10 \) is \( \boxed{703} \).