Question

Determinați valoarea numărului x stiind că a + b = 8.
a) x + 3a + 3b = 25
e) X-( 5a+ 5b ) = 70
b) 5a + x + 5b = 60
f) xa + xb + 16 = 116
c) ax + bx = 16
g) 7a + 7b - x = 50
d) 10x + ax + bx = 120
h) xa + xb + 9a + 9b = 400

Answer 1

Răspuns:

a) x+3a+3b=25

x +3(a+b)=25

x+3×8=25

x+24=25

x=25-24

x=1

e)x-(5a+5b)=70

x-5(a+b)=70

x-5×8=70

x-40=70

x=70+40

x=110

c) ax + bx = 16

x(a+b)=16

x×8=16

x=16÷8

x=2

b) 5a + x + 5b = 60

5a+5b+x=60

5(a+b) + x=60

5×8+ x =60

40+x=60

x=60-40

x=20

f) xa + xb + 16 = 116

x(a+b)+16=116

x×8+16=116

x×8=116-16

x×8=100

x=100÷8

x=12.5

g) 7a + 7b - x = 50

7(a+b)-x =50

7 × 8 -x = 50

56-x=50

-x=50-56

-x=-6

x=6

d) 10x + ax + bx = 120

10x+x(a+b)=120

10x+8x=120

18x=120

x=120pe 18

h) xa + xb + 9a + 9b = 400

x(a+b) + 9(a+b)=400

x×8+9×8=400

8x+72=400

8x=400-72

8x=328

x=328÷8

x=41