Question

ajutatima si pe mn cu exercitiile de mai sus va rog!!Dau coroana si 20 de pct

Answer 1

Răspuns

Explicație pas cu pas:

5(x - 1) = x + 7

5x - 5 = x + 7

4x = 12

x = 3

_________

2(x + 3) - 5 = x - 7

2x + 6 - 5 = x - 7

2x + 1 = x - 7

x = -8

____________

2x + 5si2/3 = 2si1/4

2x = 9/4 - 17/3 = 27/12 - 68/12 = -41/12

x = -41/24

__________

4(x + 5) - 5(x + 3) = 6x - 5(x + 1)

4x + 20 - 5x - 15 = 6x - 5x - 5

-x + 5 = x - 5

2x = 10

x = 5

_________

(x+5)/3 + (2x +3)/4 = (x-5)/6 + 7/12

numitor comun este 12

4(x + 5) + 3(2x + 3) = 2(x - 5) + 7

4x + 20 + 6x + 9 = 2x -10 + 7

10x + 29 = 2x - 3

8x = -32

x = -4

__________

(x + 4)/5 - (x + 2)/3 = 2x/15 - (x + 1)/3

numitor comun este 15

3(x + 4) - 5(x + 2) = 2x - 5(x + 1)

3x + 12 -5x -10 = 2x -5x -5

-2x + 2 = -3x - 5

x = -7

____________

Prima zi: 10%

A doua zi: 30%

A treia zi: 42 km

In cele doua zile parcurge 10% + 30% = 40%

A treia zi: 100% - 40% = 60% = 42 km

Drumul are 42 x 100 / 60 = 70 km

(Verificare: 10% = 7 km; 30% = 21 km; 70 - 7 -21 = 42 km)

________

Prima zi: 2S/5 + 300

Rest: S - 2S/5 - 300 = 5S/5 - 2S/5 - 300 = 3S/5 - 300

A doua zi: 2/3 * (3S/5 - 300) + 100

Rest

S - (2S/5 + 300) - {2/3 * (3S/5 - 300) + 100} = 2380

S - 2S/5 - 300 - (2S/5 - 200 + 100) = 2380

S - 2S/5 -300 -2S/5 + 200 - 100 = 2380

S - 4S/5 - 200 = 2380

5S/5 - 4S/5 = 2380 + 200

S/5 = 2580

S = 5 * 2580 = 12900