Ask two junior high school math questions

subject

In the schematic diagram of rectangular Bao Shu paper shown in Figure 1, the dotted line is the crease, the shadow is the cut part, the four corners are squares with the same size, and the side length of the square is the folded width.

(1) As shown in Figure 2, the book of Thinking Games is 2 1cm in length, 0/5cm in width and 0/cm in thickness. This book is wrapped in a rectangular piece of paper with an area of 875cm2, which is unfolded as shown in figure 1. Find the width of the fold;

(2) If there is a rectangular Bao Shu paper with a length of 60cm and a width of 50cm, two books as shown in Figure 2 are wrapped, and the edges of the books are parallel to the edges of Bao Shu paper. After cutting, wrapping and unfolding, it is as shown in figure 1. What is the maximum width of the fold?

analyse

(1) rectangular area =(2 width+1+2 fold width) × (length +2 fold width);

(2) Answer according to the different positions of books. The relationship is: the total length after placement is ≤ 60; The total length after placement is ≤50.

explain

Solution:

( 1)

Let the folding width be xcm.

Then (2x+15x2+1) (2x+21) = 875.

Simplify:

x？ +26x-56=0

∴x=2 or -28 (irrelevant, omitted)

That is, the width folded in is 2 cm;

(2)

Let the folding width be xcm, then:

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