a. 7x -2 +2x >13x -8
9x -13x > -8 +2 - 4x > - 6 : ( -2) x< 3/2 x∈( -∞ , 3/2)
b. 8 ( 2x-3 ) < 20 -3
16x -24 < 17 16x < 17 +24 16x < 41 x< 41 /16; x∈(-∞, 41/16)
c. 3 ( x² -1) + x² +4x+4 > 4x² -4x +1
3x² -3 +x²+ 4x+4+ -4x² +4x > 1
8x +1 > 1 8x>0 x>0 x∈( 0 , +∞ )