Question

Calculati:
a) ab+ac, Stiind ca b+c=50 si a =2

b)xy+xz+15, Stiind ca x=9 si y + z=11

c)ab-ac, Stiind ca a=7 si b-c=100

d)5xy+5xz+21, Stiind ca x=4 si y+z=100

Answer 1

a)  b + c = 50   si   a = 2

a b + a c = a × ( b + c ) = 2 × 50 = 100

b)   x = 9   si   y + z = 11

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

c)     a = 7   si b - c = 100

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

d)    x = 4   si   y + z = 100

5 x y + 5 x z + 21 = 5 × X × ( y + z ) + 21 = 5 × 4 × 100 + 21 = 2 000 + 21 = 2 021