Răspuns
Explicație pas cu pas:
a + b = 4 si c = 5
a)
5 a + 5 b + 3 c = 35
= 5 × ( a + b ) + 3 × 5 =
= 5 × 4 + 15 =
= 20 + 15 =
= 35
_____________
b)
( 4 a + 4 b + c ) × [ 3 c - ( 2 a + 2 b ) ] = 147
= [ 4 × ( a + b ) + 5 ] × [ 3 × 5 - 2 × ( a + b ) ] =
= ( 4 × 4 + 5 ) × ( 15 - 2 × 4 ) =
= ( 16 + 5 ) × ( 15 - 8 ) =
= 21 × 7 =
= 147
