Răspuns:
1. a) 1005x241-1005×240=1005x(241-240)=1005x1=1005
b)735x37+735x63=735(37+63)=735x100=73500
c)653+653x24+653x977=653x(1+24+977)=654x1002
d)(1+2+3+...+61):102=(62x61)÷2:102=31×31÷102
e)1+3+5+...+79=(80×40)÷2=40×40
f)39+40+41+...+57=(96x19)÷2=48x19
g)5+10+15+....+130=5x(1+2+3+...+26)=5x27×26÷2=5x27x13
h)5x-5y-6=5(x-y)-6=5x12-6=60-6=54
2)a×b+a×c+a×d=a×(b+c+d)=a×28=5628
a=201
3)a+b=40 => 3a+3b=120
b+c=57 => 5b+5c=285
3a+3b+5b+5c=3a+8b+5c=285+120=405
3a+8b+5c=405
Explicație pas cu pas:
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