The length of each cuboid in the figure below is 2cm and the width is 1cm. When the cuboid is stacked to four layers, the perimeter of the stacked figure is () cm. If the cuboid is stacked to a figure, it is () cm It's 126 cm. It's going to be stacked in () layers

The length of each cuboid in the figure below is 2cm and the width is 1cm. When the cuboid is stacked to four layers, the perimeter of the stacked figure is () cm. If the cuboid is stacked to a figure, it is () cm It's 126 cm. It's going to be stacked in () layers

Hello, first question: 24cm. This question has a certain regularity. The perimeter of the X layer can be regarded as the total perimeter of the horizontal and vertical directions, or the edge line can be translated. For example, in the second layer, In fact, it's a perimeter that consists of two rectangles at the top and two rectangles at the bottom. Similarly, the perimeter of layer x is the perimeter that consists of two rectangles at the top and two rectangles at the bottom. Layer 4: perimeter = (2 * 4 + 4 * 1) * 2 = 24cm
Then (2 * x + 1 * x) * 2 = 126 and x = 21
Then y = (2 * x + 1 * x) * 2 = 6x
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A rectangle is 18cm long and 10cm wide. Cut a square 2cm long on each side at its four corners. The perimeter of the remaining figure () a becomes larger and B smaller
C unchanged

Hello!
A rectangle is 18cm long and 10cm wide. Cut a square 2cm long on each side at its four corners. The perimeter of the remaining figure (c)
A. Bigger B, smaller C, unchanged
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A rectangle is 10 cm long and 6 cm wide. If the four corners of the rectangle are cut out of the square with a side length of 1 cm, the perimeter of the remaining figure ()
A. Add 4cm B. add 8cm
C reduced by 4cm D. same as before

D. Equal to the original