Question

Mình lay hoay mãi vẫn kbt câu trl b nào rảnh lm giúp mình với ạ,nhanh mình sẽ tick ạ!

Answer 1

14: \(\dfrac{1}{7}x\left(\dfrac{3}{5}x-0,75x\right)=-\dfrac{1}{35}\)

=>\(x\left(\dfrac{3}{5}x-\dfrac{3}{4}x\right)=-\dfrac{1}{5}\)

=>\(x\cdot\dfrac{-3}{20}x=-\dfrac{1}{5}\)

=>\(x^2=\dfrac{1}{5}:\dfrac{3}{20}=\dfrac{1}{5}\cdot\dfrac{20}{3}=\dfrac{4}{3}\)

=>\(x=\pm\dfrac{2\sqrt{3}}{3}\)

15: \(\dfrac{1}{5}x-\left(0,25x-\dfrac{1}{3}x\right)+\dfrac{-8}{45}=0\)

=>\(\dfrac{1}{5}x-\left(\dfrac{1}{4}x-\dfrac{1}{3}x\right)=\dfrac{8}{45}\)

=>\(\dfrac{1}{5}x-\dfrac{-1}{12}x=\dfrac{8}{45}\)

=>\(x\cdot\dfrac{17}{60}=\dfrac{8}{45}\)

=>\(x=\dfrac{8}{45}:\dfrac{17}{60}=\dfrac{8}{45}\cdot\dfrac{60}{17}=8\cdot\dfrac{4}{3\cdot17}=\dfrac{32}{51}\)