Re: [問題] 請教幾題數學
If x=√0.25, then what is the approximate value of √x? (m)
(A) 0.50
(B) 0.62
(C) 0.71
(D) 1.22
(E) 1.41
答案為C
x=√0.25=0.5
√x = √0.5≒0.71
(0.71x0.71=0.5041)
If a, b,and c are one of the values of 0, 1 or 2, and 3^2xa+3xb+c=25, what is
the value of a+b+c? (m)
(A) 2
(B) 3
(C) 4
(D) 5
(E) 6
答案為D
3^2xa+3xb+c=25
9a+3b+c=25
9x2+3x2+1=25
∥ ∥ ∥
a b c
a+b+c=2+2+1=5
If each side length of a pyramid whose base is a square is 10 centimeters, what
is the distance from the tip of the pyramid to the center of its square base?
(A) 2√2
(B) 5
(C) 5√2
(D) 10
(E) 10√2
答案為C
10^2=(5√2)^2+X^2
100=50+X2
X^2=50
X=5√2
If the length of a rectangle is increased by 15% and the width is decreased by
10%, which of the following is the percent increase in the area of the
rectangle? (m-h)
(A) 3.5%
(B) 4.5%
(C) 5.5%
(D) 6.5%
(E) 7.5%
答案為A
L L'=1.15L
W W'=0.9W
L'xW'=1x15Lx0.9W=1.035LW
L'xW'-LW=0.035LW
0.035LW/LWx100%=3.5%
（以上內容由美加 黃冠文老師提供）
※ 引述《audrey0906 (audrey0906)》之銘言：
: If x=√0.25, then what is the approximate
: value of √x? (m)
: (A) 0.50
: (B) 0.62
: (C) 0.71
: (D) 1.22
: (E) 1.41
: 答案為C
: If a, b,and c are one of the values of 0, 1 or 2, and
: 3^2xa+3xb+c=25, what is the value of
: a+b+c? (m)
: (A) 2
: (B) 3
: (C) 4
: (D) 5
: (E) 6
: 答案為D
: If each side length of a pyramid whose base is a square is 10 centimeters, what is the distance from the tip of the pyramid to the center of its square base?
: (A) 2√2
: (B) 5
: (C) 5√2
: (D) 10
: (E) 10√2
: 答案為C
: If the length of a rectangle is increased by 15% and
: the width is decreased by 10%, which of the following is the percent increase in the area of the rectangle? (m-h)
: (A) 3.5%
: (B) 4.5%
: (C) 5.5%
: (D) 6.5%
: (E) 7.5%
: 答案為A
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