when using multiplying by 1 to find an expression equivalent to 18/7 with a denominator of 28x, the equivalent expression that I get is 4x/28x and i am being told that that's wrong
Let's look at this:
The original value is 18/7. You want to find an equivalent value that has a denominator of 28. To get that value, you need to multiply the denominator by 4. To "multiply by 1" to not change the value, you need to also multiply the numerator by 4.
So:
(18 x 4)/(7 x 4) = ?/28
When multiplying fractions, we can multiply both the numerator and the denominator by the same number to create an equivalent fraction. In this case, we want to find an expression equivalent to 18/7 with a denominator of 28x.
To do this, let's multiply the numerator and denominator of 18/7 by 4x (since 28x divided by 7 is 4x):
(18/7) * (4x/4x)
Multiplying the numerators and the denominators gives us:
(18 * 4x) / (7 * 4x)
Now, let's simplify the expression:
72x / 28x
To determine if this is the correct equivalent expression, we can simplify it further by canceling out common factors:
(9 * 8x) / (7 * 4x)
9 and 8 have no common factors, so we cannot cancel them out.
However, we can cancel out the common factor of x:
9 * 8 / 7 * 4
72 / 28
The expression simplifies to:
36/14
Therefore, the equivalent expression to 18/7 with a denominator of 28x is 36/14, not 4x/28x.
It's important to simplify the expression fully before determining if it is equivalent to the original fraction.