Toán Lớp 6: Giải giúp mình với mình cần gấp Bài 1 : Tìm x 2^x-3-26=6 64.4^2x+2=4^9 9.3^x-1=243 2^2.3^x=972 3^4.3^x=3^7 3^x+25=26.2^2+2.3^0 B

Question

Toán Lớp 6:  Giải giúp mình với mình cần gấp Bài 1 : Tìm x 2^x-3-26=6        64.4^2x+2=4^9 9.3^x-1=243 2^2.3^x=972 3^4.3^x=3^7 3^x+25=26.2^2+2.3^0 Bài 2 : Tìm x thuộc N 3^x-2.3=243 2^2x-6.16^2=1024 64.4^x-3=16^8 5^2x-1-10^2=5^2 Bài 3:Tìm số tự nhiên x, biết (2x-2)^4=16 (2x+1)^3=125 (7x-11)^3+2^5.5^2+200 (x+3)^3.12=324

daithanh · Answer

1)   2^(x-3)-26=6   2^(x+3)=6+26   2^(x+3)=32   2^(x+3)=2^5   =>x+3=5   =>x=5-3   =>x=2   64.4^(2x+2)=4^9   4^(2x+2)=4^9:4^3   4^(2x+2)=4^6   =>2x+2=6   =>2x=6-2   =>2x=4   =>x=4:2   =>x=2   9.3^(x-1)=243   3^(x-1)=3^5:3^2   3^(x-1)=3^3   =>x-1=3   =>x=3+1   =>x=4   2^2. 3^x=972   3^x=972:4   3^x=243   3^x=3^5   =>x=5   3^4. 3^x=3^7   3^x=3^7:3^4   3^x=3^3   =>x=3   3^x+25=26.2^2+2.3^0   3^x+25=104+2   3^x+25=106   3^x=106-25   3^x=81   3^x=3^4   =>x=4   2)   3^(x-2).3=243   3^(x-2)=243:3   3^(x-2)=81   3^(x-2)=3^4   =>x-2=4   =>x=4+2   =>x=6   2^(2x-6).16^2=1024   2^(2x-6)=1024:256   2^(2x-6)=4   2^(2x-6)=2^2   =>2x-6=2   =>2x=2+6   =>2x=8   =>x=8:2   =>x=4   64.4^(x-3)=16^8   4^3. 4^(x-3)=(4^2)^8   4^(x-3)=4^16:4^3   4^(x-3)=4^13   =>x-3=13   =>x=13+3   =>x=16   5^(2x-1)-10^2=5^2   5^(2x-1)=25+100   5^(2x-1)=125   5^(2x-1)=5^3   =>2x-1=3   =>2x=3+1   =>2x=4   =>x=4:2   =>x=2   3)   (2x-2)^4=16   (2x-2)^4=2^4   =>2x-2=2   =>2x=2+2   =>2x=4   =>x=4:2   =>x=2   (2x+1)^3=125   (2x+1)^3=5^3   =>2x+1=5   =>2x=5-1   =>2x=4   =>x=4:2   =>x=2   (7x-11)^3+2^5. 5^2+200(sai)    (x+3)^3. 12=324     (x+3)^3=324:12     (x+3)^3=27     (x+3)^3=3^3     =>x+3=3     =>x=3-3     =>x=0