Question

Cunoscand ca $\frac{a}{b}$ = $\frac{3}{7}$ calculati valoarea expresiei $\frac{5a-b}{2a+3b}$

Answer 1

$a=\frac{3}{7}b$

Expresia devine:

$\dfrac{5\cdot\frac{3}{7}b-b}{2\cdot\frac{3}{7}b+3b}=\dfrac{b\left(5\cdot\frac{3}{7}-1\right)}{b\left(2\cdot\frac{3}{7}+3\right)}=...$

Simplifici pe $b$  și faci calculele.

Answer 2

a=3b/7

(5*3b/7 -b)  supra (2*3b/7 +3b)

(15b/7-b)  supra (6b/7+3b)   aducem la acelasi numitor in paranteze

(15b-7b)/7   supra (6b+7b)/7

8b/7  supra 13b/7=

=8b/7 * 7/13b  se simplifica si ne da

=8/13