a) Multiply through by 2x2-x:
x2+4x+6x-3=21,
x2+10x-24=(x+12)(x-2)=0, so x=-12 or 2.
CHECK: (-8)/(-25)+3/(-12)=8/25-1/4=(32-25)/100=7/100; 21/(288+12)=21/300=7/100.
6/3+3/2=7/2; 21/6=7/2.
b) |2x+4|=-8. No solution because absolutes can't be negative.
c) 2m2-3m-7=0; m=(3±√(9+56))/4=(3±√65)/4; m=(3+√65)/4 or (3-√65)/4.
d) √(4y+7)=y+1, 4y+7=y2+2y+1, y2-2y=6, y2-2y+1=7, (y-1)2=7, y=1±√7. However, y=1-√7 doesn't satisfy the original equation, so solution is y=1+√7.
e) y4-7y2+12=0=(y2-4)(y2-3), y=±2 or ±√3 (4 possible solutions).