UC知道gre 数学提问
来源：百度知道 编辑：UC知道 时间：2024/07/08 17:34:54
题目1：At a sale, the cost of each tie was reduced by 20% and the cost of each belt was reduced by 30%
The percent reduction on the total cost of 1 tie and 2 belts 和 25% 比较大小
题目2：For the line with equation y=ax+ b,ab 不为零 the x intercept is twice the y intercept
The slope of the line 和 1/2 比较大小
The percent reduction on the total cost of 1 tie and 2 belts 和 25% 比较大小
题目2：For the line with equation y=ax+ b,ab 不为零 the x intercept is twice the y intercept
The slope of the line 和 1/2 比较大小
[Problem 1]
Solution :
1 tie: Original price : t
Reduced by : 0.2t
2 belts : Original price : 2b
Reduced by : 0.6b
The percentage reduction =(0.2t+0.6b)/(t+2b)=0.2x(1+1/(2+t/b))
So 20%<Ans<30% (条件不明，无确切解）
[Problem 2]
Solution :
y=ax+b,
Let modulus of (-b/a)=modulus of (2b)
So,modulus of a = 0.5
i.e. a = 1/2 or a = -1/2
楼上给的是正确的 …………
第一题和第二题都是D