Răspuns:
1.a)3x + 12=0 <=> 3x= -12 <=> x = -12/3
b) 4x-5=0<=> 4x=5 <=> x=5/4
2.a) 2x-3=0 <=> 2x=3 <=> x=2/3
b) radical din 7 x -2 =0 <=> radical din 7 x = 2 <=> x= 2/ radical din 7
3. la a nu mai stiu, am o varsta, si nu imi mai aduc nici eu aminte tot
b)
[tex]\frac{3}{4} x - 5\sqrt{7} = 0 <=> \frac{3}{4} x - \frac{20\sqrt{7} }{4} = 0 <=> 3x- 20 \sqrt{7} = 0 <=> 3x = 20\sqrt{7} <=> x= \frac{20\sqrt{7} }{3}[/tex]
4. a ) 4x+a = 2x +3 <=> 4x-2x=3-a <=>2x= 3-a <=> 2 x=3+2 <=> 2x =5 <=> x=5/2
5.
[tex]\frac{x-2}{3} + \frac{x+1 }{2} =1\\inmultim fiecare fractie : prima o inmultim cu 2 , a doua cu 3\\ne rezulta => 2(x-2) + 3(x+1) =1 <=> 2x-4 + 3x + 3 =1 <=> 5x -1 = 1 <=> 5x = 1+1 <=> 5x=2 <=> x=2/5\\\\\\[/tex]
6.a+b=300
b=5a
a+5a=300
6a=300
a=300:6
a=50
b=5x50=250
