( 2^3.3^2 - 5^4:5^2 ) + 2017^0
Đề ôn thi giúp mik nhé!!Mơn trc.
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\(30+2x=4^{2017}:4^{2015}\)
\(\Rightarrow30+2x=4^2=16\)
\(\Rightarrow2x=16-30=-14\)
\(\Rightarrow x=-14:2=-7\)
30 + 2x = 42017 : 42015
30 + 2x = 42
30 + 2x = 16
2x = 16 - 30
2x = -14
x = - 7
x^3 - 3x^2 + x + 5 = 0
=> x^3 + x^2 - 4x^2 - 4x + 5x + 5 = 0
=> x^2(x + 1) - 4x(x + 1) + 5(x + 1) = 0
=> (x^2 - 4x + 5)(x + 1) = 0
x^2 - 4x + 5 > 0
=> x + 1 = 0
=> x = -1
\(=\dfrac{33}{17}\cdot\dfrac{34}{3}\cdot\dfrac{2}{5}=\dfrac{2\cdot11\cdot2}{5}=\dfrac{44}{5}\)
\(\dfrac{33}{17}\times\dfrac{34}{3}\times\dfrac{2}{5}=11\times2\times\dfrac{2}{5}=\dfrac{44}{5}\)
\(\sqrt{x^2-2x+4}+\sqrt{x^2+5}=9-2x\left(đk:x\le\dfrac{9}{2}\right)\)
\(\Leftrightarrow x^2-2x+4+x^2+5+2\sqrt{\left(x^2-2x+4\right)\left(x^2+5\right)}=81-36x+4x^2\)
\(\Leftrightarrow2\sqrt{\left(x^2-2x+4\right)\left(x^2+5\right)}=2x^2-34x+72\)
\(\Leftrightarrow4\left(x^2-2x+4\right)\left(x^2+5\right)=4x^4+1156x^2+5184-136x^3+288x^2-4896x\)
\(\Leftrightarrow4x^4-8x^3+36x^2-40x+80=4x^4-136x^3+1444x^2-4896x+5184\)
\(\Leftrightarrow128x^3-1408x^2+4856x-5104=0\)
\(\Leftrightarrow128x^2\left(x-2\right)-1152x\left(x-2\right)+2552\left(x-2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(128x^2-1152x+2552\right)=0\)
\(\Leftrightarrow x=2\left(tm\right)\)(do \(128x^2-1152x+2552>0\))
4/5 + 5/6 : 3/2
= 4/5 + 5/9
= 61/45
3/5 : 4/6 - 3/1
= 9/10 - .3
= -21/10
4/6 : 5/4 + 3/2
= 8/15 + 3/2
= 61/30
\(\frac{4}{5}\)+ \(\frac{5}{6}\): \(\frac{3}{2}\)= \(\frac{61}{45}\)
\(\frac{3}{5}\): \(\frac{4}{6}\)- \(\frac{3}{1}\)= - \(\frac{21}{10}\)= -2,1
\(\frac{4}{6}\): \(\frac{5}{4}\)+ \(\frac{3}{2}\)= \(\frac{61}{30}\)
\((2^3\cdot3^2-5^4:5^2)+2017^0\)
\(=(8\cdot9-5^{4-2})+2017^0\)
\(=(8\cdot9-5^2)+2017^0\)
\(=(72-25)+2017^0\)
\(=47+2017^0\)
\(=47+1=48\)
Chúc bạn học tốt :>