Question

Dacă x = 5 și a + b = 13, calculați: (Cu explicatie)

a) 3 ⋅ x + 7 ⋅ a + 7 ⋅ b ;

c) 10 ⋅ x + (4 ⋅ a + 4 ⋅ b) ;b) x ⋅ a + x ⋅ b– 50 ;

d) (4 ⋅ a + 4 ⋅ b– 2 ⋅ x) ⋅ (2 ⋅ a + 2 ⋅ b + x).

Answer 1

Răspuns:

a) 3•x+7•a+7×b=15+7•(a+b)=15+7•13=15+91=106

b)x•a+x•b-50=x(a+b)-50=5•13-50=65-50=15

c)10•x+(4•a+4•b)=50+4(a+b)=50+4•13=50+52=102

d)(4•a+4•b-2•x)•(2•a+2•b+x)=[4(a+b)-2•x]•[2(a+b)+x]=(4•13-10)•(2•13+5)=(52-10)•(26+5)=42•31=1302