(2.x-4)*2=58
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a,\(\int\limits^{\frac{\Pi}{6}}_0\frac{sin\left(2x+x\right)}{cos^2x}dx=\int\limits^{\frac{\Pi}{6}}_0\frac{sin2x.cosx+cos2x.sinx}{cos^2x}dx=\int\limits^{\frac{\Pi}{6}}_0\frac{2cos^2x.sinx+\left(2cos^2x-1\right)sinx}{cos^2x}dx=\int\limits^{\frac{\Pi}{6}}_0\frac{4cos^2x.sinx}{cos^2x}dx+\int\limits^{\frac{\Pi}{6}}_0\frac{d\left(cosx\right)}{cos^2x}=\int\limits^{\frac{\Pi}{6}}_0sinxdx-\frac{1}{cosx}\)
thay cận vào nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
a) Ta có: \(7-\left(2x+4\right)=-\left(x+4\right)\)
\(\Leftrightarrow7-2x-4=-x-4\)
\(\Leftrightarrow-2x+3+x+4=0\)
\(\Leftrightarrow-x+7=0\)
\(\Leftrightarrow-x=-7\)
hay x=7
Vậy: S={7}
b) Ta có: \(\dfrac{2+x}{5}-0.5x=\dfrac{1-2x}{4}+0.25\)
\(\Leftrightarrow\dfrac{4\left(2+x\right)}{20}-\dfrac{0.5x\cdot20}{20}=\dfrac{5\left(1-2x\right)}{20}+\dfrac{20\cdot0.25}{20}\)
\(\Leftrightarrow4\left(2+x\right)-10x=5\left(1-2x\right)+5\)
\(\Leftrightarrow8+4x-10x=5-10x+5\)
\(\Leftrightarrow-6x+8=-10x+10\)
\(\Leftrightarrow-6x+8+10x-10=0\)
\(\Leftrightarrow4x-2=0\)
\(\Leftrightarrow4x=2\)
hay \(x=\dfrac{1}{2}\)
Vậy: \(S=\left\{\dfrac{1}{2}\right\}\)
d) Ta có: \(\dfrac{x-1}{59}+\dfrac{x-2}{58}+\dfrac{x-3}{57}=\dfrac{x-59}{1}+\dfrac{x-58}{2}+\dfrac{x-57}{3}\)
\(\Leftrightarrow\dfrac{x-1}{59}-1+\dfrac{x-2}{58}-1+\dfrac{x-3}{57}-1=\dfrac{x-59}{1}-1+\dfrac{x-58}{2}-1+\dfrac{x-57}{3}-1\)
\(\Leftrightarrow\dfrac{x-60}{59}+\dfrac{x-60}{58}+\dfrac{x-60}{57}=\dfrac{x-60}{1}+\dfrac{x-60}{2}+\dfrac{x-60}{3}\)
\(\Leftrightarrow\left(x-60\right)\left(\dfrac{1}{59}+\dfrac{1}{58}+\dfrac{1}{57}\right)-\left(x-60\right)\left(1+\dfrac{1}{2}+\dfrac{1}{3}\right)=0\)
\(\Leftrightarrow\left(x-60\right)\left(\dfrac{1}{59}+\dfrac{1}{58}+\dfrac{1}{57}-1-\dfrac{1}{2}-\dfrac{1}{3}\right)=0\)
mà \(\dfrac{1}{59}+\dfrac{1}{58}+\dfrac{1}{57}-1-\dfrac{1}{2}-\dfrac{1}{3}\ne0\)
nên x-60=0
hay x=60
Vậy: S={60}
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(x-452=77+48\)
\(=>x-452=125\)
\(=>x=125+452\)
\(=>x=577\)
____
b) \(x+58=64+58\)
\(=>x+58=122\)
\(=>x=122-58\)
\(=>x=64\)
_____
c) \(x-1-2-3-4=0\)
\(=>x-10=0\)
\(=>x=0+10\)
\(=>x=10\)
![](https://rs.olm.vn/images/avt/0.png?1311)
x - 452 = 77 + 48
x-452=125
x=452+125
x=577
x + 58 = 64 + 58
x+58=122
x=122-58
x=64
x - 1 - 2 - 3 - 4 = 0
x-(1+2+3+4)=0
x-10=0
x=10+0
x=10
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) x - 452 = 77 + 48
x-452=125
x=577
b) x+58 = 64 + 58
x+58=122
x=64
c)x - 1 - 2 - 3 - 4 = 0
x-1-2-3=4
x-1-2=7
x-1=9
x=10
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(\dfrac{x+1}{55}+\dfrac{x+2}{56}+\dfrac{x+3}{57}+\dfrac{x+4}{58}\right)-4=0\)
<=>\(\dfrac{x+1}{55}+\dfrac{x+2}{56}+\dfrac{x+3}{57}+\dfrac{x+4}{58}=4\)
<=>\(\dfrac{x+1}{55}-1+\dfrac{x+2}{56}-1+\dfrac{x+3}{57}+\dfrac{x+4}{58}-1=4-4\)
<=>\(\dfrac{x+1}{55}-\dfrac{55}{55}+\dfrac{x+2}{56}-\dfrac{56}{56}+\dfrac{x+3}{57}-\dfrac{57}{57}+\dfrac{x+4}{58}-\dfrac{58}{58}=0\)
<=>\(\dfrac{x-54}{55}+\dfrac{x-54}{56}+\dfrac{x-54}{57}+\dfrac{x-54}{58}=0\)
<=>\(\left(x-54\right)\left(\dfrac{1}{55}+\dfrac{1}{56}+\dfrac{1}{57}+\dfrac{1}{58}\right)=0\)
<=>x-54=0
<=>x=54
vậy phương trình có tập nghiệm là S={54}
(2x-4)*2=58 4x-8=58. 4x=66. x=66:4 x=16.5