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一元方程式的應用題 (英): 一元方程式的應用題
- The perimeter of Tina's rectangular garden is 60 feet.
- If the length of the garden is twice the width - the length is twice the width -
- what are the dimensions of the garden?
- So, let's draw this garden here: Tina's garden.
- So it's a rectangle - they tell us that it's a rectangular garden -
- So, it looks something like this.
- And let's say that this is the width.
- So if this is the width, then this is also going to be the width.
- And this is the length up here.
- And they tell us that the length of the garden is twice the width.
- So, if this is w, then the length is going to be 2w.
- It's going to be twice the width.
- This is also going to be 2w over here.
- Now, what's the perimeter of this garden?
- Well, it's going to be w+w+2w+2w - let me write this down -
- The perimeter of this garden is going to be w+2w+w+2w,
- which is equal to what?
- This is w plus 2w is 3w -
- 4w, 6w. So this is equal to 6w.
- That's the perimeter in terms of the width.
- They also tell us that the actual numerical value of the perimeter is 60 feet -
- it is 60 feet.
- So, this perimeter 6w must be equal to 60 if we're assume that we're dealing with feet.
- So, we just have the equation 6w=60.
- We can divide both sides of this equation by 6,
- so that we have just a w on the left hand side.
- 6w divided by 6 is just w
- and then 60 divided by 6 is 10.
- So, we have w=10.
- So this, the width of the garden is 10.
- So, this distance over here is 10.
- And then, what is the length of the garden?
- Well, it's two times the width.
- So, this is equal to 20.
- The length is equal to 20.
- And so, we're done.
- This is a 20 by 10 garden.