Từ tỉ lệ thức \(\dfrac{a}{b}=\dfrac{c}{d};\left(a,b,c,d\ne0;a\ne\pm b;c\ne\pm d\right)\), hãy suy ra các tỉ lệ thức sau :
a) \(\dfrac{a+b}{b}=\dfrac{c+d}{d}\)
b) \(\dfrac{a-b}{b}=\dfrac{c-d}{d}\)
c) \(\dfrac{a+b}{a}=\dfrac{c+d}{c}\)
d) \(\dfrac{a-b}{a}=\dfrac{c-d}{c}\)
e) \(\dfrac{a}{a+b}=\dfrac{c}{c+d}\)
f) \(\dfrac{a}{a-b}=\dfrac{c}{c-d}\)
Bài 2: tính
a, \(\dfrac{11}{24}-\dfrac{5}{41}+\dfrac{13}{24}+0,5-\dfrac{36}{41}\)
b,\(-12:\left(\dfrac{3}{4}-\dfrac{5}{6}\right)^2\)
c,\(\dfrac{7}{23}.[\left(-\dfrac{8}{6}\right)-\dfrac{45}{18}]\)
d,\(23\dfrac{1}{4}.\dfrac{7}{5}-13\dfrac{1}{4}:\dfrac{5}{7}\)
e,\(\left(1+\dfrac{2}{3}-\dfrac{1}{4}\right).\left(0,8-\dfrac{3}{4}\right)^2\)
a)\(\dfrac{5}{15}+\dfrac{14}{25}-\dfrac{12}{9}+\dfrac{2}{7}+\dfrac{11}{25}\)
b)\(\left(\dfrac{3}{7}-\dfrac{5}{2}-\dfrac{3}{5}\right)-\left(-\dfrac{4}{7}-\dfrac{3}{2}+\dfrac{2}{5}\right)\)
c)\(\left(\dfrac{2}{5}\right)^2+5\dfrac{1}{2}.\left(4,5-2\right)+\dfrac{2^3}{\left(-4\right)}\)
d)\(\left(-\dfrac{1}{2}\right)^2:\dfrac{1}{4}-2.\left(-\dfrac{1}{2}\right)^3\)
e)\(\sqrt{16}.1\dfrac{3}{4}+\dfrac{1}{4}-7\)
f)\(\dfrac{2^9.4^{10}}{8^8}\)
Bài 1:
a) Thực hiện phép tính: \(\dfrac{17}{13}\)-\(\dfrac{5}{3}\)
b) Cho tam giác ABC có góc A=70o và gócB=65o . Tính số đo của góc C.
Bài 2:
a) Tìm x biết: \(x+3\dfrac{1}{2}=\dfrac{11}{5}\)
b) Vẽ đồ thị của hàm số y = 3x
c) Tính nhanh: \(\left(\dfrac{-3}{7}+\dfrac{5}{11}\right):\dfrac{4}{31}+\left(\dfrac{-4}{7}+\dfrac{6}{11}\right):\dfrac{4}{31}\)
a,Tìm x,y,z biết: \(\dfrac{y+z+1}{x}\)=\(\dfrac{x+z+2}{y}\)=\(\dfrac{x+y-3}{z}\)=\(\dfrac{1}{x+y+z}\)
b,Cho \(\dfrac{a}{b}\)=\(\dfrac{b}{c}\)=\(\dfrac{c}{d}\). Chứng minh rằng: (\(\dfrac{a+b+c}{b+c+d}\))3=\(\dfrac{a}{d}\)
c,Cho \(\dfrac{a}{b}\)=\(\dfrac{c}{d}\). Chứng minh rằng: \(\dfrac{5a+3b}{5c+3d}\)=\(\dfrac{5a-3b}{5c-3d}\)
d,Cho \(\dfrac{3x-2y}{4}\)=\(\dfrac{2z-4x}{3}\)=\(\dfrac{4y-3z}{2}\).Chứng minh rằng: \(\dfrac{x}{2}\)=\(\dfrac{y}{3}\)=\(\dfrac{z}{4}\)
Bài 1: Tìm x, biết
a,\(\dfrac{1}{2}+\dfrac{2}{3}.x=\dfrac{4}{5}\)
b,\(x+\dfrac{1}{4}=\dfrac{4}{3}\)
c,\(\dfrac{3}{5}x-\dfrac{1}{2}=-\dfrac{1}{7}\)
d,\(|x-\dfrac{4}{5}|=\dfrac{3}{4}\)
e,\(\dfrac{1}{2}-lxl=\dfrac{1}{3}\)
1.Tìm số hữu tỉ có dạng \(\dfrac{7}{a}\) biết \(\dfrac{-9}{11}\)<\(\dfrac{7}{a}\)<\(\dfrac{-9}{13}\)
2.Cho x thỏa mãn x2=1.Hỏi x có là số hữu tỉ không ?
3.Cho a,b\(\in\)Z ,b>0.Hãy so sánh:
a,\(\dfrac{a}{b}\)và\(\dfrac{a+2018}{b+2018}\)
b,\(\dfrac{a}{b}\)và\(\dfrac{a+n}{b+n}\)(n\(\in\)N*)
Tính
N=\(\dfrac{2a+b+c+d}{a}=\dfrac{a+2b+c+d}{b}=\dfrac{a+b+2c+d}{c}=\dfrac{a+b+c+2d}{d}\)
Biết
N=\(\dfrac{a+b}{c+d}+\dfrac{b+c}{d+a}+\dfrac{c+d}{a+b}+\dfrac{d+a}{b+c}\)
GIẢI ĐƯỢC BẰNG HAI CÁCH THÌ CÀNG TỐT
mn giúp mk vs
a)\(\dfrac{x-3}{4}=\dfrac{4}{x=3}\)
b)(x-1);5=(2x+1):3
c)\(\dfrac{37-x}{x+13}=\dfrac{3}{7}\)
d)\(\dfrac{x-1}{x+2}=\dfrac{x-2}{x+1}\)
e) \(\dfrac{x+4}{20}=\dfrac{5}{x+4}\)
