Question

Urgent ex 4 si 5 din imagine la 12:10 întru la ore si prima este matematica!Dau 10 puncte plus coroana!URGENT VA ROG AJUTATI MĂ!!!!!Pls

Answer 1

4.

a)  b + c = 50   si   a = 2

ab + ac = a ( b + c ) = 2 × 50 = 100

b)   x y + x z + 15 =?

x = 9   si   y + z = 11

x y + x z + 15 = x ( y + z ) + 15 = 9 × 11 + 15 = 99 + 15 = 114

c)    a b - a c = a × ( b - c )=?

a = 7   si b - c = 100

a b - a c = a × ( b - c ) = 7 × 100 = 700

d)    5 x y + 5 x z + 21 =?

x = 4   si   y + z = 100

5 x y + 5 x z + 21 = 5 × X × ( y + z ) + 21 = 5 × 4 × 100 + 21 = 2000 + 21 = 2021

5.

a) x + 3 × a - 3 × b = 20

x + 3 × (a - b) = 20

x + 3 × 6 = 20⇒x + 18 = 20⇒x = 2

b) x × a - x × b + 9a - 9b = 654

x×(a - b) + 9(a - b) = 654

x× 6 + 9 × 6 = 654

6x = 654 - 54⇒6x = 600⇒ x = 100

c) 7 × a - 7 × b + x = 55

7×(a  - b) + x = 55

7×6 + x = 55

x = 55 - 42 = 13

d) 13 + x - (5a - 5b) = 2011

13 + x - [5(a - b)] = 2011

13 + x - 5 × 6 = 2011

x = 2011 - 13 + 30=2028