Question

VA ROG URGENT DAU COROANA CINE MA AJUTA CELE 4 exercitii sau cele pe care le stiti

Answer 1

1.
x - suma initiala
In prima zi x/4 (25%=25/100=1/4)
In a doua zi 3x/10 (30%=30/100=3/10)
In a treia zi 270 lei
x/4 + 3x/10 + 270 = x
Numitor comun 20
5x+6x+5400=20x
5400=20x-11x
5400=9x =>x=600 lei

2.
3[2(10x-5-13)-17]=81
2(10x-5-13)-17=27
2(10x-5-13)=44
10x-18=22
10x=40
x=4

3.
Numitor comun 6
3(x+2)²-2(x²-9)=3(2x-1)+(x-1)²
3(x²+4x+4)-2x²+18=6x-3+x²-2x+1
3x²+12x+12-2x²+18=4x-2+x²
x²+12x+30=x²+4x-2
12x-4x=-30-2
8x=-32 
x=-4

4.
Fie x - intregul drum
In prima zi - 2x/5 (40%=40/100=2/5) =>rest 3x/5 (pana la un intreg de 5x/5)
In a doua zi - 3/8 · 3x/5 = 9x/40
In a treia zi - 36 km
2x/5 + 9x/40 + 36 = x
Numitor comun 40
16x+9x+1440=40x
1440=40x-25x
1440=15x
x=96 km