Răspuns:
Explicație pas cu pas:
3) x = 5 si a + b = 13
a) 3 x + 7 × a + 7 × b = 106
= 3 × 5 + 7 × ( a + b ) =
= 15 + 7 × 13 =
= 15 + 91 =
= 106
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c) 10 x + 4 × a + 4 × b = 102
= 10 × 5 + 4 × ( a + b ) =
= 50 + 4 × 13 =
= 50 + 52 =
= 102
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b ) x - a + x - 50 = - a - 50 -> exercitiu incomplet
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d)
( 4 × a + 4 × b - 2 × x ) × ( 2 × a + 2 × b + x ) = 1 302
= ( 4 × 13 - 2 × 5 ) × ( 2 × 13 + 5 ) =
= ( 52 - 10 ) × ( 26 + 5 ) =
= 42 × 31 =
= 1 302
