Math  /  Algebra

Questionyy varles inversely as xx. If x=2x=2 then y=7y=7. Find yy when x=4x=4. \square y=y= Submit Question

Studdy Solution

STEP 1

What is this asking? If yy changes inversely with xx, and we know one pair of xx and yy values, what will yy be when xx is a different value? Watch out! Inverse variation means as one variable goes up, the other goes down, but not by simple addition or subtraction!
It's all about multiplication.

STEP 2

1. Set up the inverse variation equation.
2. Find the constant of variation.
3. Solve for the new *y* value.

STEP 3

Alright, so we know that yy varies inversely with xx.
What does that *actually* mean?
It means that their product is always the same, a **constant**!
We can write this relationship as yx=ky \cdot x = k, where kk is our **constant of variation**.

STEP 4

We're given that when x=2x = 2, then y=7y = 7.
Let's plug those **values** into our equation: 72=k7 \cdot 2 = k.

STEP 5

This gives us k=14k = 14.
So, our **constant of variation** is 14\textbf{14}!
Our equation is now yx=14y \cdot x = 14.

STEP 6

Now, we want to find yy when x=4x = 4.
Let's plug in x=4x = 4 into our equation: y4=14y \cdot 4 = 14.

STEP 7

To solve for yy, we need to divide both sides of the equation by 44: y44=144 \frac{y \cdot 4}{4} = \frac{14}{4} This simplifies to: y=144 y = \frac{14}{4}

STEP 8

Now, we simplify the fraction.
Both the numerator and denominator are divisible by 22, so we get: y=144=72 y = \frac{14}{4} = \frac{7}{2} So, when x=4x = 4, y=72y = \frac{7}{2}!

STEP 9

When x=4x = 4, y=72y = \frac{7}{2}.

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