y is directly proportional to the square of (x - 1). y = 63 when x = 4. Find the value of y when x = 6.
Understand the Problem
The question is asking us to find the value of y when x = 6, given that y is directly proportional to the square of (x - 1) and that y equals 63 when x is 4. To solve this, we will establish the relationship between y and x using the direct proportionality condition and then calculate y for x = 6.
Answer
The value of \( y \) when \( x = 6 \) is \( y = 175 \).
Answer for screen readers
The value of ( y ) when ( x = 6 ) is ( y = 175 ).
Steps to Solve
- Establish the proportional relationship
Since ( y ) is directly proportional to the square of ( (x - 1) ), we can express this relationship as:
$$ y = k(x - 1)^2 $$
where ( k ) is the proportionality constant.
- Determine the value of ( k )
We know from the problem that ( y = 63 ) when ( x = 4 ). Substituting these values into the equation:
$$ 63 = k(4 - 1)^2 $$
This simplifies to:
$$ 63 = k(3^2) $$
which gives:
$$ 63 = 9k $$
Solving for ( k ):
$$ k = \frac{63}{9} = 7 $$
- Substitute ( k ) back into the equation
Now that we have ( k ), we can rewrite the equation for ( y ):
$$ y = 7(x - 1)^2 $$
- Calculate ( y ) when ( x = 6 )
Substituting ( x = 6 ) into the equation:
$$ y = 7(6 - 1)^2 $$
This simplifies to:
$$ y = 7(5^2) $$
Calculating further:
$$ y = 7 \times 25 $$
- Final calculation
Completing the multiplication gives:
$$ y = 175 $$
The value of ( y ) when ( x = 6 ) is ( y = 175 ).
More Information
In problems involving direct proportionality, it’s crucial to first find the proportionality constant by using initial conditions. Here, we found ( k = 7 ), which allowed us to compute ( y ) for any value of ( x ) based on our established relationship.
Tips
- Forgetting to square ( (x - 1) ): Ensure to follow the problem’s specifications about squaring the expression correctly.
- Miscalculating the proportionality constant: Double-check calculations to avoid arithmetic errors.
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