Question

Daca a+b=4 si c=5,calculati:
a) 5a+3c+5b=?
b) (4a+c+4b) x [3c-(2a+2b)]=?

Answer 1

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