Toán Lớp 6: Giải dùm em bài này a)(-3x-4)-2=2.(-3)mũ 2 b)2-(3x-4)=-18 c)(x-1)-(-15)=30 d)735+(218-x)=541 e)(5x-75):2-84=201 g)[(-3)+2].x=[(-3)+(-6

Question

Toán Lớp 6:  Giải dùm em bài này  a)(-3x-4)-2=2.(-3)mũ 2 b)2-(3x-4)=-18 c)(x-1)-(-15)=30 d)735+(218-x)=541 e)(5x-75):2-84=201 g)[(-3)+2].x=[(-3)+(-6)] h)23-3.(x+4)=128

mocmien87 · Answer

a) (-3x-4)-2= 2.(-3)&sup2;   (-3x-4)-2= 2.9   (-3x-4)-2= 18   -3x-4= 18+2   -3x-4= 20   -3x= 20+4   -3x= 24   x= 24:(-3)   x= -8   b)2-(3x-4)= -18   3x-4= 2-(-18)   3x-4= 2+18   3x-4= 20   3x= 20+4   3x= 24   x= 24:3   x= 8   c)(x-1)-(-15)= 30   (x-1)+15= 30   x-1= 30-15   x-1= 15   x= 15+1   x= 16   d) 735+(218-x)= 541   218-x= 541-735   218-x= -194   x= 218-(-194)   x= 218+194   x= 412   e) (5x-75):2-84=201   (5x-75):2= 201+84   (5x-75):2= 285   5x-75= 285.2   5x-75= 570   5x= 570+75   5x= 645   x= 645:5   x= 129   g)[(-3)+2].x= [(-3)+(-6)]   (-1).x= -9   x= -9:(-1)   x= 9   h) 23-3.(x+4)= 128   3.(x+4)= 23-128   3.(x+4)= -105   x+4= -105:3   x+4= -35   x= -35-4   x= -39   @Na

maingoctruc · Answer

a) (-3x - 4) - 2 = 2 xx (-3)^2   => (-3x - 4) - 2 = 2 xx 9   => (-3x - 4) - 2 = 18   => -3x - 4 = 18 + 2   => -3x - 4 = 20   => -3x = 20 + 4   => -3x = 24   => x = 24 : (-3)   => x = -8   --------------------------------   b) 2 - (3x - 4) = -18   => 3x - 4 = 2 - (-18)   => 3x - 4 = 20   => 3x = 20 + 4   => 3x = 24   => x = 24 : 3   => x = 8   --------------------------------   c) (x - 1) - (-15) = 30   => x - 1 = 30 + (-15)   => x - 1 = 15   => x = 15 + 1   => x = 16   --------------------------------   d) 735 + (218 - x) = 541   => 218 - x = 541 - 735   => 218 - x = -194   => x = 218 - (-194)   => x = 412   --------------------------------   e) (5x - 75) : 2 - 84 = 201   => (5x - 75) : 2 = 201 + 84   => (5x - 75) : 2 = 285   => 5x - 75 = 285 xx 2   => 5x - 75 = 570   => 5x = 570 + 75   => 5x = 645   => x = 645 : 5   => x = 129   --------------------------------   g) [(-3) + 2] xx x = [(-3) + (-6)]   => (-1) xx x = -9   => x = (-9) : (-1)   => x = 9   --------------------------------   h) 23 - 3 xx (x + 4) = 128   => 3 xx (x + 4) = 23 - 128   => 3 xx (x + 4) = -105   => x + 4 = (-105) : 3   => x + 4 = -35   => x = (-35) - 4   => x = -39