Toán Lớp 7: Bài 1:tìm x: a) (x+2)^2=4 b) (x+3)^4=16

Question

Toán Lớp 7:  Bài 1:tìm x: a) (x+2)^2=4 b) (x+3)^4=16

annhocbichchaubich · Answer

***Lời giải*** a) (x+2)^2=4 <=>x+2= sqrt{4} => ( left[ begin{array}{l}x+2=2 x+2=-2 end{array} right. ) <=> ( left[ begin{array}{l}x=2-2 x=-2-2 end{array} right. ) <=> ( left[ begin{array}{l}x=0 x=-4 end{array} right. ) Vậy x=0 hoặc x=-4 b) (x+3)^4=16 <=>$x+3= sqrt[4]{16} $ => ( left[ begin{array}{l}x+3=2 x+3=-2 end{array} right. ) <=> ( left[ begin{array}{l}x=2-3 x=-2-3 end{array} right. ) <=> ( left[ begin{array}{l}x=-1 x=-5 end{array} right. ) Vậy x=-1 hoặc x=-5

giahan44 · Answer

#Sad   a)   (x+2)^2 = 4   &hArr; (x+2)^2 = (+-2)^2   &hArr;  ( left[  begin{array}{l}x+2=2  x+2=-2 end{array}  right. )    &hArr;  ( left[  begin{array}{l}x=0  x=-4 end{array}  right. )     text{Vậy} x=0  text{hoặc} x=-4   b)   (x+3)^4 = 16   &hArr; (x+3)^4 = (+-2)^4   &hArr;  ( left[  begin{array}{l}x+3=2  x+3=-2 end{array}  right. )    &hArr;  ( left[  begin{array}{l}x=-1  x=-5 end{array}  right. )     text{Vậy} x=-1  text{hoặc} x=-5