Toán Lớp 6: tìm x a (2x-1)²=49 b 4x+2x=68-2^19:2^16 giúp mik với ạ

Question

Toán Lớp 6:  tìm x a  (2x-1)²=49 b  4x+2x=68-2^19:2^16 giúp mik với ạ

ngoclandiep · Answer

a) ( 2x - 1 )^2 = 49   ( 2x - 1 )^2 = 7^2   $ text{&rArr; 2x - 1 = 7 hoặc 2x - 1 = - 7}$   $ text{&rArr; 2 . x = 7 + 1 hoặc 2 . x = - 7 + 1}$   $ text{&rArr; x = 8 : 2 hoặc x = - 6 : 2}$   $ text{&rArr; x = 4 hoặc x = - 3}$   b) 4x + 2x = 68 - 2^19 : 2^16   x . ( 4 + 2 ) = 68 - 2^3   x . 6 = 60   x = 60 : 6   x = 10

quynhmaithu · Answer

Lời giải chi tiết:     a) (2x-1)^2=49   => ( left[  begin{array}{l}(2x-1)^2=7^2  (2x-1)^2=(-7)^2 end{array}  right. )   => ( left[  begin{array}{l}2x-1=7  2x-1=-7 end{array}  right. )   => ( left[  begin{array}{l}2x=7+1  2x=-7+1 end{array}  right. )   => ( left[  begin{array}{l}2x=8  2x=-6 end{array}  right. )   => ( left[  begin{array}{l}x=8:2  x=-6:2 end{array}  right. )   => ( left[  begin{array}{l}x=4  x=-3 end{array}  right. )   Vậy x=4 hoặc x=-3   b) 4x+2x=68-2^19:2^16   =>x.(4+2)=68-2^(19-16)   =>x.6=68-2^3   =>x.6=68-8   =>x.6=60   =>x=60:6   =>x=10   Vậy x=10