Prep Math求救啊

Elaine85415

+  X   Y   Z                     In the addtion table shown above, what is the Value of M+N

4  1  -5   M                     answer is 5 

e  7   n  10                    为什么啊,图都没有看懂

f   2   -4   5

2.  The perimeter of a certain isosceles right triangle is 16+16根号2

       what is the length of the hypotenuse of the triangle?

       答案是16  why?

3 A contractor combined X tones of a gravel mixture that contained 10 percent gravel, by weight, with y tones of a mixture that contained 2 percent gravel,by weight,to produce Z tons of a mixture that was 5 percent gravel ,by weight. what is the value of X

(1) y=10

(2) Z=16

answer is E. 不理解

ocivv

题目1漏条件，每一行得数字是这个数字最上面的数字加上最左面数字的和

题目2，2x+根号2*x=16+16根号2 得x=8根号2，斜边就是再乘以根号2

题目3，无法算出总的gravel重多少……

Friskies

以下是引用Elaine85415在2007-9-20 20:27:00的发言：

3 A contractor combined X tones of a gravel mixture that contained 10 percent gravel, by weight, with y tones of a mixture that contained 2 percent gravel,by weight,to produce Z tons of a mixture that was 5 percent gravel ,by weight. what is the value of X

(1) y=10

(2) Z=16

answer is E. 不理解

晕，MM你答案都抄错了，这题选D

根据题意可以列出两个方程，

x+y=z

10%X+2%Y=5%Z

第一个方程可以改写成Y用Z表示，或Z用Y表示，带入另一个方程就行了

Elaine85415

+  X   Y   Z                     In the addtion table shown above, what is the Value of M+N

4  1  -5   M                     answer is 5 

e  7   n  10                    为什么啊,图都没有看懂

f   2   -4   5

没有少条件啊,我就是原题抄的.OCIVV, 可是我还是不懂啊.其他两个懂了.谢谢楼上的MM

谢谢

Elaine85415

哦,懂了.谢谢大家