Question

tìm x trog các tỉ lệ thức

a , 17-x / x+13 = 3/7

b, x+1 /2x +1 = 0,5x + 2 / x +3

c, x/3,15 = 0, 15 / 7,2

d, x mũ 2 / 6 = 24 /25

giúp vs

Answer 1

c,\(\dfrac{17-x}{x+37}=\dfrac{3}{7}\\ \)

\(\left(17-x\right).7=\left(x+13\right).3\)

\(17.7-x.7=x.3+13.3\)

\(119-7x=39+3x\)

\(119-39=3x+7x\)

\(80=10x\)

\(x=80:10\)

\(x=8\)

Answer 2

Nhầm.Đấy là phần a

Answer 3

c.\(\dfrac{x}{3,15}=\dfrac{0,15}{7,2}\)

\(x.\dfrac{36}{5}\)=\(\dfrac{3}{20}.\dfrac{15}{4}\)

\(x.\dfrac{36}{5}\)=\(\dfrac{9}{16}\)

x=\(\dfrac{9}{16}:\dfrac{36}{5}\)

x=\(\dfrac{5}{64}\)

d.\(\dfrac{x^2}{6}=\dfrac{24}{25}\)

\(x^2.25=6.24\)

\(x^2.25=144\)

\(x^2=\dfrac{144}{25}\)

\(x^2=\left(\dfrac{12}{5}\right)^2\)

⇒ \(x=\dfrac{12}{5}\)