Question

Daca a=18 b+c=57 calculati valorile ecpresiilor: a)a+b+c b)a+5×b+5×c c)3×a+2×b+2×c d)a×b+a×c+7×b+7×c

Answer 1

a) a+b+c=18+57=75
b) a+5×(b+c)=18+5×57=18+285=303
c) 3×18+2×57=54+114=168

Answer 2

a = 18   si   b + c = 57

a)   a + b + c = 18 + 57 = 75

b)   a + 5 × b + 5 × c = 18 + 5 × ( b + c ) = 18 + 5 × 57 = 18 + 285 = 303

c )   3 × a + 2 × b + 2 × c = 3 × 18 + 2 × ( b + c ) = 54 + 2 × 57 = 54 + 114 = 168

d)    a × b + a × c + 7 × b + 7 × c = 1 425

= a × ( b + c ) + 7 × ( b + c ) =

= 18 × 57 + 7 × 57 =   ⇔  1 026 + 399 = 1 425

= 57 × ( 18 + 7 ) = → am dat factor comun pe 57

= 57 × 25 =

= 1 425