▶3m^4n=-2⇒m^4n=-2/3
▶1)-12m^4n=-12*(m^4n)=-12*(-2/3)=-8
▶2)3m^8n^2=3*(m^4n)²=3*(-2/3)²=3*4/9=4/3=1 1/3
9*3^x+3^x/3<28
3^x(9+1/3)<28
3^x(28/3)<28
3^x<3^1
x<1
9^x-3^x-6>0
3^x=t t>0
t^2-t-6>0
t=3 t=-2
t>3
3^x>3
x>1
5*5^2x+4*5^x-1>0
5^x=t
5*t^2+4*t-1>0
t=(-2+sqrt(4+5))/5=1/5
t>1/5
5^x>1/5
x>-1