Question

doza ta de mate zilnica

a+b+c•d=65

b=a•2
c=b
d=a


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Answer 1

răspuns+explicație pas cu pas:

[tex]b=2a\\ [/tex]

$c=b => c=2a$

[tex]a+b+c*d=a+2a+2a*a=2a^{2} +3a\\ [/tex]

[tex]=> 2a^{2} +3a=65 => 2a^{2} +3a-65=0\\ delta=(3)^{2} -4*2*(-65)=9+520=529 \\ a_{1}=\frac{-3+\sqrt{delta} }{2*2}=\frac{-3+23}{4}=\frac{20}{4}=5\\ a_{2}=\frac{-3-\sqrt{delta} }{2*2}=\frac{-3-23}{4}=\frac{-26}{4}=\frac{-13}{2}=-6,5 \\[/tex]

[tex]cazul 1:\\ a=5 \\ b=2*5=10\\ c=b=10\\ d=a=5\\[/tex]

[tex]cazul 2:\\ a=-6,5\\ b=2*(-6,5)=-13\\ c=b=-13\\ d=a=-6,5[/tex]