Răspuns :
( 4 × a + 4 × b - 2 × x ) × ( 2 × a + 2 × b + x ) = 1 302
=[ 4 × ( a + b ) - 2 × 5 ] × [ 2 × ( a + b ) + 5 ] =
= ( 4 × 13 - 10 ) × ( 2 × 13 + 5 ) =
= ( 52 - 10 ) × ( 26 + 5 ) =
= 42 × 31 =
= 1 302
=(4(a+b)-2x5)x(2(a+b)+5)
=(4x13-10)x(2x13+5)
=(52-10)x(26+5)
=42x31
=1302