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=85*15-85*28-15*85-15*28
=(85*15-15*85)+(-85*28-15*28)
=28(-85-28)
=28*(-113)
=-3164
\(a,x:\left(-\frac{15}{28}\right)=\frac{21}{35}\)
\(x=\frac{21}{35}\times\left(-\frac{15}{28}\right)\)
\(x=-\frac{9}{28}\)
\(b,x-\frac{1}{42}=-\frac{6}{7}\times\frac{5}{7}\)
\(x-\frac{1}{42}=-\frac{30}{49}\)
\(x=-\frac{30}{49}+\frac{1}{42}\)
\(x=-\frac{173}{294}\)
\(c,\left(x-\frac{3}{4}\right):\frac{7}{5}=-\frac{1}{4}\)
\(x-\frac{3}{4}=-\frac{1}{4}\times\frac{7}{5}\)
\(x-\frac{3}{4}=-\frac{7}{20}\)
\(x=-\frac{7}{20}+\frac{3}{4}\)
\(x=\frac{2}{5}\)
a)x:-15/28=21/35
x=21/35.-15/28
x=-9/28
b)x-1/42= -6/7.5/7
x-1/42= -6/7.5/7
x-1/42=-30/49
x=-30/49+1/42
x=-173/294
c)(x-3/4):7/5=-1/4
x-3/4=-1/4.7/5
x-3/4=-7/20
x=-7/20+3/4
x=2/5
có gì sai xin tha thứ giùm nha!
hi hi!!!
\(5.\left(x+35\right)=515\)
\(x+35=515:5\)
\(x+35=103\)
\(x=103-35\)
\(\Rightarrow x=68\)
\(\left(x+40\right).15=75.12\)
\(\Rightarrow\left(x+40\right)=5.12\)[ rút gọn theo t/c đẳng thức ]
\(x+40=60\)
\(x=20\)
a,21*35-3*25*7
=21*35-21*25
=21*(35-25)
=21*10
=210
b,77-11*(30+7)
=77-11*30-11*7
=11*30=330
c,
a) \(39-x+\left[28-\left(48-2\cdot13\right)\right]=-15\)
\(39-x+\left[28-\left(48-26\right)\right]=-15\)
\(39-x+\left[28-24\right]=-15\)
\(39-x+4=-15\)
\(39-x=-15-4=-19\)
\(x=39-\left(-19\right)=58\)
xong ý A rùi
b) \(\left(-45\right)-x-\left[126-\left(52-165\right)\right]=85-22\)
\(\left(-45\right)-x-\left[125-\left(-113\right)\right]=63\)
\(\left(-45\right)-x-238=63\)
\(\left(-45\right)-x=63+238=301\)
\(x=\left(-45\right)-301=-346\)
xong ý B rùi
a) 324-(112+324) = 324-112-324 = 0 -112 = (-112)
b) 53.(-15) + (-15)*47 = (-15)*(53+47) = (-15)*100 = -1500
c)43*(53-6) + 53*(-43) = 43*53 - 43*6 + 43*(-53)= 43*(53-53) - 43*6 = 0 - 258 = (-258)
d)(192 - 37 +85) - (85+192) = 192 -37 +85 -85 -192 = 0 -0 -37 = (-37)
10h18p ngày 1/5/2020
85 : (6x - 7) + 15 = 28
6x-7= 85/13
6x= 85/13+ 13/13=98/13
x=49/39
85 : (6x - 7) + 15 = 28
85 : (6x - 7) = 28 - 15
85 : (6x - 7) = 13
(6x - 7) = 85 : 13
(6x - 7) = `85/13`
6x = `85/13` + 7
6x = `176/13`
x = `176/13` : 6
x = `88/39`.