Question

* Fie egalitatea (x + y + z)² = x² + y² +z² + 2xy+ 2yz + 2zx. Verificați egalitatea pentru:
a) x = y = z = 10;
| b) x = 2; y = 3; z = 4.
VA ROG REPEDE CU EXPLICATII!​

Answer 1

Răspuns:

$(10 + 10 + 10) ^{2} = {10}^{2} + {10}^{2} + {10}^{2} + 2 \times 10 \times 10 + 2 \times 10 \times 10 + 2 \times 10 \times 10 \\ {30}^{2} = 300 + 200 + 200 + 200 = 900 \\ \\ {(2 + 3 + 4)}^{2} = {2}^{2} + {3}^{2} + {4}^{2} + 2 \times 2 \times 3 + 2 \times 3 \times 4 + 2 \times 4 \times 2 \\ {9}^{2} = 4 + 9 + 16 + 12 + 24 + 16 \\ \\ 81 = 81$