Giả sử X là vành tùy ý, Z là vành các số nguyên. Xét tập E = X × Z, trên E ta định nghĩa 2 phép toán như sau:
(x1, n1)+(x2, n2) = (x1+x2, n1+n2), (x1, n1)∗(x2, n2) = (x1x2+n1x2+n2x1, n1n2)
Chứng minh rằng:
a. E là vành có đơn vị.
b. Hàm f : X → E xác định bởi f(x) = (x, 0) là đơn cấu (vành).

answer: approximately 206 bones

i hope this u out a branlist and a would be greatly appreciated :

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

i saw this question before, dont know the asnwer srry

step-by-step explanation: