我想一題MC
suppose x varies jointly as y^2 and the reciprocal of z. If y is decreased by 20% and z is decreased by 20%, find the percentage change of x.
A.decreased by 10%
B.decreased by 20%
C.decreased by 24%
D.decreased by 60%
answer is B
MATH mc
2009-09-04 4:41 am
回答 (1)
2009-09-04 4:48 am
✔ 最佳答案
x1 = ky2/zx2 = k(0.8y)2/(0.8z)
x2 = k(0.64y2)/(0.8z)
x2 = (0.64/0.8)(ky2/z)
x2 = 0.8(ky2/z)
x2 = 0.8x1
x2 = (1 - 20%)x1
x is decreased by 20%
收錄日期: 2021-04-23 23:18:36
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