Question

va rog ajutati-ma cu asta : (x+8)•7•(x+8)=50 !!! 

Answer 1

$(x+8) ^{2} *7=50$

$(x^{2}+16x+64) *7=50$

$7x^{2}+112x+448=50$

$7x^{2}+112x+448-50=0$

$7x^{2}+112x+398=0$

Δ=$b ^{2} -4ac=(112) ^{2}-4*7*398= 12544-11144=1400$

$x_{1} = \frac{-b- \sqrt{delta} }{2a} = \frac{-112- \sqrt{1400} }{2*7} =\frac{-112-10 \sqrt{14} }{14}=\frac{-112- 37,41 }{14}=-10,67$

$x_{2} = \frac{-b+ \sqrt{delta} }{2a} = \frac{-112+ \sqrt{1400} }{2*7} =\frac{-112+10 \sqrt{14} }{14}=\frac{-112+ 37,41 }{14}=-5,97$

x∈{$\frac{-112-10 \sqrt{14} }{14}$,$\frac{-112+10 \sqrt{14} }{14}$}
sau x∈{-10,67;-5,97}