幾題代入法的選擇題,好急(20分)

1.If x = [y(z-3)]/32, then z =?
x = [y(z-3)]/3
y(z-3) = 32x
z – 3 = 32x/y
z = 32x/y + 3
題目無答案，你可能寫錯題目。
A.3/(3x-y) B.-3/(3x-y) C.3x/(3x-y) D.-3y/(3x-y) E.(3x-y)/3y

2.If a = (1+b)/(1-b), then b = ?
a = (1+b)/(1-b)
a(1-b) = 1+b
a – ab = 1 + b
ab + b = a – 1
b(a+1) = (a-1)
b = (a-1)/(a+1) ………答案D
A.(a-1)/2 B.(a-1)/2a C.(a+1)/(a-1) D.(a-1)/(a+1) E.(1-a)/(a+1)

3.If A = (h/2)(a+b) , then b = ?
2A = h(a + b)
2A = ha + hb
hb = 2A-ha
b = (2A-ha)/h = (2A/h)-a ………答案E
A.2A-ah B.(2/h)(A-a) C.(2A-a)/h D.a-(2A/h) E.(2A/h)-a

4.If a = 2-[1/(1+b)] , then b = ?
1/(1+b) = 2 – a
1 + b = 1/(2-a)
b = 1/(2-a) – 1
= [1–(2-a)]/(2-a)
= (a–1)/(2–a)
= (1-a)/(a-2) ……… 答案A
A.(1-a)/(a-2) B.(a-1)/(a-2) C.(a+1)/(a-2) D.(-a+3)/(a-2) E.(1-a)/a

5.If x/(1+x) = a/(1-a) , then x = ?
x/(1+x) = a/(1-a)
(1+x)/x = (1-a)/a
(1/x) + 1 = (1/a) – 1
(1/x) = (1/a)-2
1/x = (1-2a)/a
x = a/(1-2a) ……… 答案D
A.a B.2a/(1-a) C.a/(1+2a) D.a/(1-2a)

1.If x = [y(z-3)]/32, then z =?
x = [y(z-3)]/3

y(z-3) = 32x

z – 3 = 32x/y

z = 32x/y + 3

題目無答案，你可能寫錯題目。

A.3/(3x-y) B.-3/(3x-y) C.3x/(3x-y) D.-3y/(3x-y) E.(3x-y)/3y

2.If a = (1+b)/(1-b), then b = ?
a = (1+b)/(1-b)

a(1-b) = 1+b

a – ab = 1 + b

ab + b = a – 1

b(a+1) = (a-1)

b = (a-1)/(a+1) ………答案D

A.(a-1)/2 B.(a-1)/2a C.(a+1)/(a-1) D.(a-1)/(a+1) E.(1-a)/(a+1)

3.If A = (h/2)(a+b) , then b = ?

2A = h(a + b)

2A = ha + hb

hb = 2A-ha

b = (2A-ha)/h = (2A/h)-a ………答案E
A.2A-ah B.(2/h)(A-a) C.(2A-a)/h D.a-(2A/h) E.(2A/h)-a

4.If a = 2-[1/(1+b)] , then b = ?

1/(1+b) = 2 – a

1 + b = 1/(2-a)

b = 1/(2-a) – 1

= [1–(2-a)]/(2-a)

= (a–1)/(2–a)

= (1-a)/(a-2) ……… 答案A

A.(1-a)/(a-2) B.(a-1)/(a-2) C.(a+1)/(a-2) D.(-a+3)/(a-2) E.(1-a)/a

5.If x/(1+x) = a/(1-a) , then x = ?
x/(1+x) = a/(1-a)

(1+x)/x = (1-a)/a

(1/x) + 1 = (1/a) – 1

(1/x) = (1/a)-2

1/x = (1-2a)/a

x = a/(1-2a) ……… 答案D

A.a B.2a/(1-a) C.a/(1+2a) D.a/(1-2a)

2.E
3.E
4.A
5.D

請問第一題有冇打錯??
我計唔到..sorry!