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Three math problems (one practical problem, 1、 Practical questions: 1. An iron block with a volume of 100 cubic centimeters is completely immersed in a rectangular container with a length of 5 cm, a width of 4 cm and a height of 20 cm. At this time, the water surface height is 12 cm. If the iron block is fished out, what is the water surface height? 1. Weld a cube with 24 cm long wire. The surface area of the cube is () A. 48 square centimeter b.36 square centimeter c.24 square centimeter 2. Saw a cuboid 12 cm in length, 9 cm in width and 5 cm in height into a cube of the same size with 3 cm in edge length. You can saw () at most A.98 B.45 C.12
1.100/(4*5)=5(cm) 12-5=7(cm)
2.C
3.C
1) Simplify (root 3 minus) ^ 2004 times (root 3 plus 2) ^ 2005 to get ()
A.-1
B. Root 3 minus 2
C. Root three plus two
D. Root 3 minus root 2
2) When x satisfies the condition________ The root sign (x + 3) / (x + 1) of the quadratic radical is meaningful
3) Estimated root 12.4 ≈_____________ (error less than 0.1)
Root 250 ≈___________ (error less than 1)
4) Satisfy the negative root sign 3
1) Simplify (root 3 minus) ^ 2004 times (root 3 plus 2) ^ 2005 to get ()
A.-1
B. Root 3 minus 2
C. Root three plus two
D. Root 3 minus root 2
Is the root 3 minus 2?
(√3-2)^2004*(√3+2)^2005
=(√3-2)^2004*(√3+2)^2004*(√3+2)
=[(√3-2)(√3+2)]^2004*(√3+2)
=(3-4)^2004*(√3+2)
=(-1)^2004*(√3+2)
=√3+2
Choose C
2) When x satisfies the condition________ The root sign (x + 3) / (x + 1) of the quadratic radical is meaningful
(x+3)/(x+1)>=0
Multiply both sides by (x + 1) ^ 2, because x + 1 is the denominator, not equal to 0
So (x + 1) ^ 2 > 0
So the inequality sign does not change direction
So (x + 3) (x + 1) > = 0
x>=-1,x
1. In the triangle ABC, angle c = 90 ° AC = 10cm, BC = 24cm, find ab
2. Simplification
Under the root sign 4Y, under the root sign 3x, under the root sign 8m square n, under the square root sign 16ab square C
3. Given the hypotenuse of a right triangle C = 21, a right triangle B = 4, find another right triangle a
(1) 26cm (2) 2 times root number y; X times root number 3x; 2Mn times root number 2; 4abc times root number C; (3) 5 times root number 17
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