Răspuns:
1) a) 4x-2 = 6
4x = 6 +2 ⇒ 4x = 8 ⇒x =8:4 ⇒x=2
b) -2x-3=-3 ⇒-2x=-3+3⇒-2x=0⇒x=0
c) -x²-x+1 =0
a= -1 b=-1 c= 1
Δ=b²- 4·a·c
Δ=(-1)²- 4·(-1)·1=1-(-4)=5
x1 = (-b+√Δ)/2a =(1+√5)/-2
x2=(-b-√Δ)/2a=(1-√5)/-2
d)x²-8x+15=0
a= 1 ; b=-8 c= 15
Δ= (-8)²-4·1·15=64-60=4
x1= (-b+√Δ)/2a =(8+√4)/2=(8+2)/2=10/2=5
x2=(-b-√Δ)/2a=(8-√4)/2=(8-2)/2=6/2=3
e)-3x²+2x+1=0
a= - 3 b =2 c= 1
Δ=4-4·(-3)·1=4+12 =16
x1 = (-2+4)/(-6)=2/-6
x2=(-2-4)/(-6)=(-6)/-6=1
f)x²+3x+2=0
a=1 b= 3 c=2
Δ=9-4·1·2=1
x1=(-3+1)/2=-2/2=-1
x2=(-3-1)/2=-4/2=-2
2)a)( 5²)³=(5)²ˣ³=5⁶
b) (3·2)³=6³
c) 4³/4²=4³⁻²=4
d) (-2)·3 - 6·(-2)=-6+12 = 6
e) -8· 1/2 +3·1/2=-8/2+3/2=-5/2
f)2 ^3/2 ·2^4/5=√2³·radical de ordin 5 din 2^4=√8·radical de ordin 5 din 16
3) 4,8989 prin lipsa este 4,8
prin adaos este 4,9
rotunjit este 5
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