题目

英语翻译
Evaluate the expression 4(2X+3)+2(X+1)-7 for each value of X.
A.1
B.6
C.22
D.12
E.Simplify the expression.When you evaluate the simplified expression for X=1 and X=6,do you get the same results as in part (a)and part (b)?
Do you get the same result for any value of
2.Why are variables useful?

提问时间：2021-02-21

答案

A.17
B.67
C.227
D.127
E.4(2X+3)+2(X+1)-7=10x+7.When x=1,the result is 17.When x=6,the result is 67.When x=22,the result is 227.When the result is 12,the result is 127.All the same results as those of not simplified expression.
2.A variable is used in algebra is useful as letter or a symbol is used instead of an unkown number.Therefore,with the help of variable,we could still do calculations or simplification of the expression containing unkown number.