Đáp án:
Giải thích các bước giải:
b22
a)2./x-1/-3x=7
2./x-1/=7+3x
Th1:
2.(x+1)=7+3x
2x+2=7+3x
2x-3x=7-2
-x=5
=>x=-5
Th2:
2.[-(x-1)]=7+3x
2.(-x+1)=7+3x
-2x+2=7+3x
-2x-3x=7-2
-5x=5
x=-1
=>x=-1
h) 5^x+5^x+2=650
5^x +5^x.5^2=650
5^x.(1+25)=650
5^x.26=650
5^x=650:26
5^x=25=5^2
=> x=2
vậy x=2
i)3^x-1 +5.3^x-1=162
3^x-1.(1+5)=162
3^x-1 . 6=162
3^x-1=162:6=27
3^x-1=3^3
=>x-1=3
x= 1+3=4
vậy x=4
b23
bài 23:
a)A=(1/2^2-1 )............(1/100^2-1)
A=(1/4-1).............(1/10000-1)
A=(-3/4)................(-9999/10000)
A=-1 .3/2.2 .-2.4/3.3 ................... -99.101/100.100
A=(-1).(-2)................(-99)/2.3.4....100 . 3.4.5.....101/2.3.4.....100
A =-1/100 . 101/2 =-101/200
vậy A=-101/200
