Question

giải các phương trình sau: 

a) 4x.(2x+3) - x.(8x-1)= 5.(x+2) 

b) (3x-5).(3x+5) - x.(9x-1) = 4 

c) 3 - 4x . (25-2x) = 8x^2 + x - 300 

d) 2. (1-3x/5) - 2+3x/10 = 7-3.(2x+1)/4 

e) 5x + 2/6 - 8x - 1 /3 = 4x + 2 /5 - 5 

f) 5x - 4/2 = 16x + 1/7 

g) 12x + 5 / 3=2x - 7/4 

h) 3t - 8/12 = 5-t /8 

i) 5u + 6/15 = u - 4 /10 

k) 3.(x-11)/4 = 3. (x+1) - 2.(2x+ 5)/10 

l) 14 và 1/2 - 2. (x+3)/5 = 3x/2 - 2. (x-7 )/3 

m ) 2x -5 / 6 - x +2 = 5x - 3/ 3 - 6x - 7/ 4 + x 

n) x-4/5 + 3x - 2/10 - x = 2x-5/3 - 7x+2/6 

mình đang cần gấp

Answer 1

a,\(4x\left(2x+3\right)-x\left(8x-1\right)=5\left(x+2\right)\)

\(< =>8x^2+12x-8x^2+x=5x+10\)

\(< =>13x=5x+10< =>8x=10\)

\(< =>x=\frac{10}{8}=\frac{5}{4}\)

b, \(\left(3x-5\right)\left(3x+5\right)-x\left(9x-1\right)=4\)

\(< =>9x^2-25-9x^2+x=4\)

\(< =>x=4+29=33\)

Answer 2

c,\(3-4x\left(25-2x\right)=8x^2+x-300\)

\(< =>3-100x+8x^2=8x^2+x-300\)

\(< =>x+100x=3+300\)

\(< =>101x=303< =>x=\frac{303}{101}=3\)

d,\(2\left(1-\frac{3x}{5}\right)-\frac{2+3x}{10}=7-\frac{3\left(2x+1\right)}{4}\)

\(< =>2-\frac{6x}{5}-\frac{2+3x}{10}=7-\frac{6x+3}{4}\)

\(< =>-\frac{24x}{20}-\frac{4+6x}{20}+\frac{30x+15}{20}=5\)

\(< =>\frac{30x-6x-24x+15-4}{20}=5\)

\(< =>\frac{11}{5}=5< =>11=25\)(vo li)

Answer 3

e,  \(\frac{5x+2}{6}-\frac{8x-1}{3}=\frac{4x+2}{5}-5\)

\(< =>\frac{25x+10}{30}-\frac{80x-10}{30}=\frac{24x+12}{30}-5\)

\(< =>\frac{24x+12+80x-10-25x-10}{30}=5\)

\(< =>79x-8=150\)

\(< =>79x=150+8< =>x=\frac{158}{79}\)

Answer 4

f, \(\frac{5x-4}{2}=\frac{16x+1}{7}\)

\(< =>\left(5x-4\right).7=\left(16x+1\right).2\)

\(< =>35x-28=32x+2\)

\(< =>35x-32x=2+28\)

\(< =>3x=30< =>x=\frac{30}{3}=10\)

Answer 5

g, \(\frac{12x+5}{3}=\frac{2x-7}{4}\)

\(< =>\left(12x+5\right).4=\left(2x-7\right).3\)

\(< =>48x+20=6x-21\)

\(< =>48x-6x=-21-20\)

\(< =>42x=-41< =>x=-\frac{41}{42}\)

Answer 6

\(\frac{3t-8}{12}=\frac{5-t}{8}\)

\(< =>\frac{\left(3t-8\right).2}{12.2}=\frac{\left(5-t\right).3}{8.3}\)

\(< =>\frac{6t-16}{24}=\frac{15-3t}{24}\)

\(< =>6t-16=15-3t\)

\(< =>6t+3t=15+16\)

\(< =>9t=31< =>t=\frac{31}{9}\)

Answer 7

\(\frac{5u+6}{15}=\frac{u-4}{10}\)

\(< =>\frac{2.\left(5u+6\right)}{30}=\frac{3\left(u-6\right)}{30}\)

\(< =>2\left(5u+6\right)=3\left(u-6\right)\)

\(< =>10u+12=3u-18\)

\(< =>7u=-18-12< =>7u=-30< =>u=-\frac{30}{7}\)

Answer 8

\(\frac{3\left(x-11\right)}{4}=3\left(x-1\right)-\frac{3\left(2x+5\right)}{10}\)

\(< =>\frac{15\left(x-11\right)}{20}=\frac{60\left(x-1\right)}{20}-\frac{6\left(2x+5\right)}{20}\)

\(< =>15\left(x-11\right)=60\left(x-1\right)-6\left(2x+5\right)\)

\(< =>15x-165=60x-60-12x-30\)

\(< =>60x-12x-15x=-165+60+30\)

\(< =>60x-27x=-165+90\)

\(< =>33x=-75< =>x=-\frac{75}{33}\)

Answer 9

\(14\frac{1}{2}-\frac{2\left(x+3\right)}{5}=\frac{3x}{2}-\frac{2\left(x-7\right)}{3}\)

\(< =>\frac{15.3x}{30}-\frac{2.10.\left(x-7\right)}{30}+\frac{2.4.\left(x+3\right)}{30}=\frac{29}{2}\)

\(< =>\frac{45x-20x+140+8x+24}{30}=\frac{29}{2}\)

\(< =>33x+164=\frac{30.29}{2}=15.29\)

\(< =>x=\frac{15.29-164}{33}\)

Answer 10

\(\frac{2x-5}{6}-x+2=\frac{5x-3}{3}-\frac{6x-7}{4}+x\)

\(< =>\frac{2\left(2x-5\right)}{12}-\frac{4\left(5x-3\right)}{12}+\frac{3\left(6x-7\right)}{12}=x+x-2\)

\(< =>\frac{4x-10}{12}-\frac{20x-12}{12}+\frac{18x-21}{12}=\frac{12\left(2x-2\right)}{12}\)

\(< =>\frac{4x-10-20x+12+18x-21}{12}=\frac{24x-24}{12}\)

\(< =>2x-29=24x-24\)

\(< =>22x=-29+24=-5< =>x=-\frac{5}{22}\)

Answer 11

\(\frac{x-4}{5}+\frac{3x-2}{10}-x=\frac{2x-5}{3}-\frac{7x+2}{6}\)

\(< =>\frac{\left(x-4\right)6}{30}+\frac{3\left(3x-2\right)}{30}-\frac{30x}{30}=\frac{10\left(2x-5\right)}{30}-\frac{5\left(7x+2\right)}{30}\)

\(< =>6x-24+9x-6-30x=20x-50-35x-10\)

\(< =>15x-30x+35x-20x=-60+30\)

\(< =>0=-30\)(vô lí)