a. 4x2-25=0
=> (2x)2-52=0
=> (2x-5)(2x+5)=0
=> 2x-5=0 hoặc 2x+5=0
=> 2x=5 hoặc 2x=-5
=> x=5:2 hoặc x=-5:2
=> x=2,5 hoặc x=-2,5
b. (x-1)(4x2-49)=0
=> (x-1)[(2x)2-72 ]=0
=> (x-1)(2x-7)(2x+7)=0
=> x-1=0 hoặc 2x-7=0 hoặc 2x+7=0
=> x=1 hoặc 2x=7 hoặc 2x=-7
=> x=1 hoặc x=7:2=3,5 hoặc x=-7:2=-3,5
Bài 1: Tìm x biết :
a) (x+2)^2 - (3x-7)^2=0
b) (4x+1) -(5x-3)^2=0
c) 25(x-3)^2 - 49(2x+1)^2=0
d) 9(3x-2)^2=121(1-4x)^2
e) (x-5/4)^2=(5x+1/2)^2
Tìm x
a) -1/2 . x = 5
b) x-1/9 = 8/3
c) x + 5/6 = 16/42 - -8/56
d) 1 3/4x - 5 = -3 1/3
e) 3 1/3 - 3/4 : x = -1/6
g) 3/x + 5 = 15%
h) 1/2 + 1/2.3 + 1/3.4 +...+1/x(x+1) = 49/50
Tìm x
a) -1/2 . x = 5
b) x-1/9 = 8/3
c) x + 5/6 = 16/42 - -8/56
d) 1 3/4x - 5 = -3 1/3
e) 3 1/3 - 3/4 : x = -1/6
g) 3/x + 5 = 15%
h) 1/2 + 1/2.3 + 1/3.4 +...+1/x(x+1) = 49/50
tìm x
a) (5-x).(x-1)<0
b) (x-4).\(\left(x+\dfrac{1}{2}\right)>hoặc=0\)
Tìm các số nguyên x, biết:
a, (22 + 5)(x2 + 25) = 0
b, (x2 + 7)(x2 - 49) < 0
c, (x2 - 7)(x2 - 49) < 0
d, (x2 - 36)(x2 - 81) ≤ 0
Tìm x
a,(4x-5).(\(\dfrac{5}{4}\)x-2)=0 b,(\(\dfrac{1}{12}\)+\(3\dfrac{1}{6}\)-30,75)x-8=(\(\dfrac{3}{5}\)+0,415+\(\dfrac{1}{200}\)):0,01
B1:Tính
a,3.52-16:22
b,22.17-23.14
c,15.141+59.10
d,17.85+15.17-120
e,100-[75-(7-2)]2
g,(23.94+93.45):(92.10-92)
B2:Tìm x
a,420+65.4=(x+175):3+30
b,96-3.(x+1)=42
c,(x-47)-115=0
d,(x-36):18=12
e,2x=16
B3:Tìm x
a,60-3.(x-2)=51
b,4x-20=25:22
c,8.6+288:(x-3)2=50
mk đang càn rất gấp
Tìm x
a,(4x-5).(5454x-2)=0
Tìm x,biết:
a)4x-(3+5x)=14
b)x2-4x=0
c)(x-3)2=4/25
