exercitii

cojocarugabry76 · Mesaj de **cojocarugabry76** » 06 Oct 2014, 16:36

3*a+2*b+4*c=494 si b+2c=160,calculeaza c si ab+ac

tata2008 · Mesaj de **tata2008** » 06 Oct 2014, 20:01

cojocarugabry76 scrie:3*a+2*b+4*c=494 si b+2c=160,calculeaza c si ab+ac

$\rm{\Large\bl\\ 3a+2c+4c=494 dar b+2c=160 |_{ \cdot 2} \rightarrow 2b+4c=320 \rightarrow 3a+320=494 \\ adic\breve{a}: 3a=494-320 =174 deci a=174 : 3 = 58 ;\\ ab+ac = ab+\underbrace{ac+ac}_{=a*2c}-ac = \underbrace{58b+58*2c}_{=58*160}-58c = ...$

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