''f'' có liên quan đến hum b??

ủa này thì sao làm đc bạn

f(x)=x+5
=) x^2+5=x+5
=)x^2=x
=)x^2-x=0
=)x(x-1)=0
=)x=0 hoặc x=1

Câu 1: C

Câu 2: A
Cau 3: C

Câu 8: C

Câu 7: A

a, 27.\(3^x\) = 243

         \(3^x\) = 243 : 27

         \(3^x\) = 9

         \(3^x\) = 3²

          \(x\) = 2

b, 49.7\(^x\) = 2041

         7\(^x\) = 2041: 49

         7\(^x\) = 41,65

           \(x\) = log₇41,56

           \(x\) ≈ 1,916

c, 64.4\(^x\)  = 4\(^5\)

          4\(^x\) = 4⁵ : 64

          4\(^x\) = 4

            \(x\) = 1

d, 3\(^x\) = 243

    3\(^x\) = 3⁵

      \(x\) = 5

e, 2\(^{x+5}\) = 128

   \(2^{x+5}\) = 2⁷

    \(x+5\) = 7

     \(x\)       = 7  - 5

       \(x\)       = 2

f, 3.3\(^x\) = 81

       3\(^x\) = 81 : 3

       3\(^x\) = 27

      3\(^x\) = 3³

       \(x\) = 3

g, 25 + 5\(^x\).5\(^x\) = 650

           5\(^{2x}\)     = 650 - 25

           5\(^{2x}\)    = 625

          5\(^{2x}\)     = 5⁴ 

            2\(x\)    = 4

              \(x\)     = 2

a: Kẻ Ox//AB

Ox//AB

=>góc xOA=góc OAB(hai góc so le trong)

=>góc xOA=41 độ

góc xOA+góc xOB=góc AOB

=>góc xOB=71-41=30 độ=góc OCD

=>Ox//CD

=>AB//CD

=>Ax//Cy

b: BD//AO

=>góc B+góc OAB=180 độ(trong cùng phía)

=>góc B=180-41=139 độ

AB//CD

=>góc B+góc D=180 độ(hai góc trong cùng phía)

=>góc D=180-139=41 độ

better not eat too much junk food

been reading that book for 2 weeks

When I arrived last night, he was watching TV

going to bed late last night, she felt tired

has watched

do-do

went-stayed

listens

doesn't play

is often

have been-wee

had walked

had finished

had moved

\(a,27.3^x=243\\ \Rightarrow3^x=243:27\\ \Rightarrow3^x=9\\ \Rightarrow3^x=3^2\\ \Rightarrow x=2\left(thoaman\right)\)

\(b,49.7^x=2041\\ \Rightarrow7^x=2041:49\\ \Rightarrow7^x=7^4:7^2\\ \Rightarrow7^x=7^{4-2}\\ \Rightarrow7^x=7^2\\ \Rightarrow x=2\left(thoaman\right)\)

\(c,64.4^x=4^5\\ \Rightarrow4^x=4^5:4^3\\ \Rightarrow4^x=4^2\\ \Rightarrow x=2\left(thoaman\right)\)

\(d,3^x=243\\ \Rightarrow3^x=3^5\\ \Rightarrow x=5\left(thoaman\right)\)

\(e,2^{x+5}=128\\ \Rightarrow2^x.2^5=2^7\\ \Rightarrow2^x=2^7:2^5\\ \Rightarrow2^x=2^2\\ \Rightarrow x=2\left(thoaman\right)\)

\(f,3.3^x=81\\ \Rightarrow3^x=81:3\\ \Rightarrow3^x=27\\ \Rightarrow3^x=3^3\\ \Rightarrow x=3\left(thoaman\right)\)

\(g,25+5^x.5^x=650\\ \Rightarrow5^{2x}=650-25\\ \Rightarrow5^{2x}=625\\ \Rightarrow5^{2x}=5^4\\ \Rightarrow2x=4\\ \Rightarrow x=4:2=2\left(thoaman\right)\)

câu h không rõ đề ? 

@seven 

1. B

2. C

3. C

4. B

5. A

6. D

7. C

8. C

9. A

10. B

1. B 2. C 3. C 4. B 5. A 6. D 7. C 8. C 9. A 10. B