Question

Calculati: 1) a x(ori) b+ a x(ori) c , stiind ca a= 3/(supra) 16 si b+c=4/9 (patru supra 9)
2) 9a+4b+5c , stiind ca a+b=10/3 (10 supra 3) si a+c=5

Answer 1

$ab+ac=a(b+c)=\frac{3}{16}*\frac{4}{9}=\frac{1}{3*4}=\frac{1}{12}$
2)$9a+4b+5c=4a+4b+5a+5c=4(a+b)+5(a+c)=4\frac{10}{3}+5*5=\frac{40}{3}+25=\frac{40+25*3}{3}=\frac{40+75}{3}=\frac{115}{3}$