Math  /  Algebra

Question20x5y=54xy=1\begin{array}{l}20 x-5 y=5 \\ 4 x-y=1\end{array}

Studdy Solution

STEP 1

What is this asking? We're trying to find the mystery values of xx and yy that make *both* of these equations true at the same time! Watch out! Don't forget, there are *two* equations here, and our xx and yy values need to satisfy both of them.
It's a team effort!

STEP 2

1. Simplify the first equation
2. Express yy in terms of xx
3. Substitute and solve for xx
4. Substitute and solve for yy

STEP 3

Look at that first equation, 20x5y=520x - 5y = 5.
Notice how all those numbers are divisible by **5**?
Let's make things easier by dividing both sides by **5**!
Remember, what we do to one side, we *must* do to the other to keep the equation balanced.
This gives us 4xy=14x - y = 1.
Much cleaner!

STEP 4

Now, let's get that yy by itself in our simplified equation.
We can do this by adding yy to both sides and subtracting 11 from both sides.
This gives us y=4x1y = 4x - 1.
Now we know what yy is in terms of xx!

STEP 5

Remember our second equation, 4xy=14x - y = 1?
Let's swap out the yy with what we just found: 4x14x - 1.
This gives us 4x(4x1)=14x - (4x - 1) = 1.

STEP 6

Now, distribute that negative sign: 4x4x+1=14x - 4x + 1 = 1.
Whoa, the 4x4x terms add to zero!
We're left with 1=11 = 1.
This means that *any* value of xx will work!

STEP 7

Since *any* xx works, let's pick a simple one: x=0x = 0.

STEP 8

Plug x=0x = 0 into our equation for yy: y=401y = 4 \cdot 0 - 1, which simplifies to y=1y = -1.

STEP 9

Just to be sure, let's try x=1x = 1.
Then y=411=3y = 4 \cdot 1 - 1 = 3.

STEP 10

There are infinitely many solutions!
Since any xx value works, we can express the solution as a set of ordered pairs: (x,4x1)(x, 4x - 1).
For example, when x=0x = 0, y=1y = -1, and when x=1x = 1, y=3y = 3.

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