Bài 1:Tìm x
1)x²+33=69
2)(x-2)²+14=63
3)15+(x+1)3=42
4)84-2×x⁴=7²+
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1: Ta có: \(20-2\left(x+4\right)=4\)
\(\Leftrightarrow2\left(x+4\right)=16\)
\(\Leftrightarrow x+4=8\)
hay x=4
5: Ta có: \(\left(x+1\right)^3=27\)
\(\Leftrightarrow x+1=3\)
hay x=2
1/ `|x|=10<=> x=\pm 10`
2/ `|x-8|=0<=>x-8=0<=>x=8`
3/ `7+|x|=12<=>|x|=5<=>x=\pm 5`
4/ `|x+1|=3`
$\Leftrightarrow\left[\begin{array}{1}x+1=3\\x+1=-3\end{array}\right.\\\Leftrightarrow\left[\begin{array}{1}x=3\\x=-4\end{array}\right.$
5/ `15-x=16-(14-42)`
`<=>15-x=16+28`
`<=>15-x=44`
`<=>x=-29`
6/ `210-(x-12)=168`
`<=>210-x+12=168`
`<=>222-x=168`
`<=>x=54`
1)\(\frac{252}{x}=\frac{84}{97}\Rightarrow\)\(\frac{84}{97}=\frac{252}{291}\Rightarrow x=291\)
6) \(\frac{y}{15}=\frac{2}{5}\Rightarrow\frac{2}{5}=\frac{6}{15}\Rightarrow x=6\)
c: Ta có: \(\dfrac{2}{5}\cdot\left[\left(\dfrac{3}{5}\right)^2:\left(-\dfrac{1}{5}\right)^2-7\right]\cdot\left(1000\right)^0\cdot\left|-\dfrac{11}{15}\right|\)
\(=\dfrac{2}{5}\cdot\left(\dfrac{9}{25}:\dfrac{1}{25}-7\right)\cdot1\cdot\dfrac{11}{15}\)
\(=\dfrac{2}{5}\cdot\dfrac{11}{15}\cdot2\)
\(=\dfrac{44}{75}\)
bài 1: tính hợp lý
a) 16+273+84+27
= (273 + 27) + (16 + 84)
= 300 + 100 = 400
b)2,5x11+2,5x89
= 2,5 x ( 11 + 89)
= 2,5 x 100 = 250
c)12x25+2x27x6+3x48x4
= 12x25 + 12x27 +12x48
= 12 x (25+27+48)
=12 x 100
=1200
1) \(x^2+33=69\)
\(x^2=36\)
\(x=\pm6\)
2) \(\left(x-2\right)^2+14=63\)
\(\left(x-2\right)^2=49\)
\(x-2=\pm7\)
\(\left[{}\begin{matrix}x=9\\x=-5\end{matrix}\right.\)
3) \(15+\left(x+1\right)^3=42\)
\(\left(x+1\right)^3=27\)
\(x+1=3\)
\(x=2\)
câu cuối chưa hết đề nha e
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