thực hiện phép tính
1/2+3/4-(3/4-4/5)
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2:
1: =>36x+14x=69+81=150
=>50x=150
=>x=3
2: 3^x=81
=>3^x=3^4
=>x=4
3: 3(2x+1)^2=75
=>(2x+1)^2=25
=>2x+1=5 hoặc 2x+1=-5
=>x=-3 hoặc x=2
1:
1: \(\dfrac{13\cdot17^4+4\cdot17^4}{17^3}-\dfrac{14\cdot3^3-14\cdot3^2}{9}\)
\(=\dfrac{17^4\cdot\left(13+4\right)}{17^3}-\dfrac{14\cdot3^2\left(3-1\right)}{9}\)
\(=17\cdot17-14\cdot2\)
=289-28
=261
2:
\(2^3\cdot5^2-\left[131-\left(23-2^3\right)^2\right]\)
\(=8\cdot25-131+\left(-1\right)^2\)
=69+1
=70
1) \(-6x^4+4x^3-2x^2\)
2) \(=x^2+4x-21-x^2-4x+5=-16\)
3) \(=6x^2-4x-x^2-4x-4=5x^2-8x-4\)
4) \(=2x^3-4x^2-8x-3x^2+6x+12=2x^3-7x^2-2x+12\)
1: \(\sqrt{3+\sqrt{5}}\cdot\sqrt{2}=\sqrt{6+2\sqrt{5}}=\sqrt{5}+1\)
3) \(\left(\sqrt{\dfrac{3}{4}}-\sqrt{3}+5\cdot\sqrt{\dfrac{4}{3}}\right)\cdot\sqrt{12}\)
\(=\left(\dfrac{\sqrt{3}}{2}-\dfrac{2\sqrt{3}}{2}+5\cdot\dfrac{2}{\sqrt{3}}\right)\cdot\sqrt{12}\)
\(=\dfrac{17\sqrt{3}}{6}\cdot2\sqrt{3}\)
\(=\dfrac{34\cdot3}{6}=\dfrac{102}{6}=17\)
1) \(\sqrt{1\dfrac{9}{16}}=\sqrt{\dfrac{25}{16}}=\dfrac{5}{4}\)
2) \(\dfrac{\sqrt{12.5}}{0.5}=\sqrt{\dfrac{12.5}{0.25}}=5\sqrt{2}\)
3) \(\sqrt{\dfrac{25}{64}}=\dfrac{5}{8}\)
4) \(\dfrac{\sqrt{230}}{\sqrt{2.3}}=\sqrt{\dfrac{230}{2.3}}=\sqrt{100}=10\)
5) \(\left(\sqrt{\dfrac{2}{3}}+\sqrt{\dfrac{50}{3}}-\sqrt{24}\right)\cdot\sqrt{6}\)
\(=\left(\dfrac{\sqrt{2}}{\sqrt{3}}+\dfrac{5\sqrt{2}}{\sqrt{3}}-2\sqrt{6}\right)\cdot\sqrt{6}\)
\(=\left(\dfrac{6\sqrt{2}}{\sqrt{3}}-2\sqrt{6}\right)\cdot\sqrt{6}\)
\(=0\cdot\sqrt{6}=0\)
Đáp án :
`-1/2`
Giải thích các bước giải :
`1/2` - (`1/3` + `2/3`)
= `1/2` - 1
= `-1/2`
________________________
Đáp án :
`7/9`
Giải thích các bước giải :
`4/9` + `1/2` . `2/3`
= `4/9` + `1/3`
= `12/27` + `9/27`
= `21/27` = `7/9`
1: \(23+\left(-13\right)+\left(-50\right)\)
\(=23-13-50\)
=10-50
=-40
2: \(-5+15+\left(-123\right)\)
\(=\left(-5+15\right)-123\)
=10-123
=-113
3: \(5871:\left\{928-\left[\left(-82+247\right)\right]\right\}\cdot5\)
\(=5871-\left\{928+82-247\right\}\cdot5\)
\(=5871-763\cdot5=5871-3815=2056\)
4: \(40-\left(4\cdot5^2-3\cdot2^3\right)\)
\(=40-4\cdot5^2+3\cdot2^3\)
\(=40-4\cdot25+3\cdot8\)
=40-100+24
=64-100
=-36
5: \(6^2\cdot5-7^2+149\)
\(=36\cdot5-49+149\)
\(=180+149-49\)
=180+100
=280
6: \(-210:\left[16+3\cdot\left(6+3\cdot2^2\right)\right]+\left(-2022\right)\)
\(=-210:\left[16+3\cdot\left(6+3\cdot4\right)\right]+\left(-2022\right)\)
\(=-210:\left[16+3\cdot18\right]+\left(-2022\right)\)
\(=-210:70-2022\)
=-3-2022
=-2025
7: \(5\cdot2^3+7^{11}:7^9-2023^0\cdot1^8\)
\(=5\cdot8+7^2-1\)
=40+49-1
=39+49
=88
8: \(400:\left\{5\cdot\left[360-\left(290+2\cdot5^2\right)\right]\right\}\)
\(=400:\left\{5\cdot\left[360-290-2\cdot25\right]\right\}\)
\(=400:\left\{5\cdot20\right\}\)
\(=\dfrac{400}{100}=4\)
9: \(75-\left(3\cdot5^2\right)-4\cdot5^3\)
\(=75-3\cdot25-4\cdot5^3\)
=-4*125
=-500
1: \(\dfrac{12}{5\sqrt{6}}=\dfrac{12\sqrt{6}}{30}=\dfrac{2\sqrt{6}}{5}\)
2: \(\dfrac{3}{2+\sqrt{6}}=\dfrac{-6+3\sqrt{6}}{2}\)
1: \(\left(x-1\right)^3-x\left(x-2\right)^2+1\)
\(=x^3-3x^2+3x-1-x^3+4x^2-4x+1\)
\(=x^2-x\)
2: \(2x\left(3x+2\right)-3x\left(2x+3\right)\)
\(=6x^2+4x-6x^2-9x\)
=-5x
\(=\frac{1}{2}+\frac{3}{4}-\frac{3}{4}+\frac{4}{5}\)
\(=\frac{1}{2}+0+\frac{4}{5}\)
\(=\frac{5}{10}+\frac{8}{10}=\frac{13}{10}=1\frac{3}{10}\)
\(\frac{1}{2}+\frac{3}{4}-\left(\frac{3}{4}-\frac{4}{5}\right)\)
\(=\frac{1}{2}+\frac{3}{4}-\frac{3}{4}+\frac{4}{5}\)
\(=\frac{1}{2}+0+\frac{4}{5}\)
\(=\frac{13}{10}\)