Question

E urgent va rog din suflet!! DAU COROANA!!!!!!
Calculati produsul A·B si raportul $\frac{B}{A}$ , unde:
a) A=$\sqrt{196}$·($\sqrt{98}$-$\sqrt{18}$+$\sqrt{162}$-$\sqrt{72}$)
B=$\sqrt{162}$·($\sqrt{343}-$-$\sqrt{175}$+$\sqrt{448}$-$\sqrt{63}$

Answer 1

Trebuie sa desfaci de sub radical pentru a ajunge intr-o forma mai simpla. De exemplu:

[tex] \sqrt{98} = 7\sqrt{2} \\ \sqrt{18}=3 \sqrt{2} \\ \sqrt{162} =9 \sqrt{2} \\ \sqrt{72} =6 \sqrt{2} \\ A=14*(7\sqrt{2}-3\sqrt{2}+9\sqrt{2}-6\sqrt{2}) \\ A=98 \sqrt{2} \\ \\ \sqrt{343} = 7\sqrt{7} \\ \sqrt{175} =5 \sqrt{7} \\ \sqrt{448} = 8\sqrt{7} \\ \sqrt{63} = 3\sqrt{7} \\ B=9 \sqrt{2} (7\sqrt{7}-5 \sqrt{7}+8\sqrt{7}-3\sqrt{7}) \\ B=63 \sqrt{14} \\ \\ A*B=98 \sqrt{2} *63 \sqrt{14} =12348 \sqrt{7} \\ \\ \frac{A}{B} = \frac{98 \sqrt{2}}{63 \sqrt{14}} = \frac{2\sqrt{7}}{9} [/tex]