(15 - x )^2 = 81
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a) Bạn Nguyễn Lê Phước Thịnh giải rồi nha bạn :)
b) (-9-x+2)+9
=-9-x+2+9
=-9+(-x)+2+9
=(-x)+(-9+2+9)
=(-x)+2
c) 66-(12-x)+(12-66)
=66-12+x+12-66
=x
d) 15-(15-x+93)+93
=15-15+x-93+93
=x
a)x+(-81)-(11-81)
=x-81-11+81
=x-11
b)(-1-x+2)+1
=-1-x+2+1
=-x+2
c)15-(11-x)+(11-15)
=15-11+x+11-15
=x
d)15-(15-x+202)+202
=15-15+x-202+202
=x
a) \(x+\left(-81\right)-\left(11-81\right)=x-81-11+81=x-11\)
b) \(\left(-1-x+2\right)+1=\left(-1\right)-x+2+1=-x+2=2-x\)
c) \(15-\left(11-x\right)+\left(11-15\right)=15-11-x+11-15\)
\(=\left(15-15\right)+\left(11-11\right)+x=0+0+x=x\)
d) \(15-\left(15-x+202\right)=15-15+x-202=x-202\)
a)x-81-11+81=x-11
b)(-1-x+2)+1=-1-x+2+1=2-x
c)15-(11-x)+(11-15)=15-11+x+11-15=x
d)15-(15-x+202)+202=15-15+x-202+202=x
\(\dfrac{4}{5}\times\dfrac{5}{8}=\dfrac{20}{40}=\dfrac{1}{2}\)
\(\dfrac{7}{15}+\dfrac{4}{5}=\dfrac{7}{15}+\dfrac{12}{15}=\dfrac{19}{15}\)
\(\dfrac{2}{3}-\dfrac{3}{8}=\dfrac{16}{24}-\dfrac{9}{24}=\dfrac{7}{24}\)
\(\dfrac{1}{2}\div\dfrac{2}{5}=\dfrac{1}{2}\times\dfrac{5}{2}=\dfrac{5}{4}\)
\(\left(15-x\right)^2=81\)
\(\Rightarrow\left(15-x\right)^2=9^2\) hoặc \(\left(15-x\right)^2=\left(-9\right)^2\)
\(\Rightarrow15-x=9\) hoặc \(15-x=-9\)
\(\Rightarrow x=15-9\) hoặc \(x=15-\left(-9\right)=15+9\)
\(\Rightarrow x=6\) hoặc \(x=24\)
Vậy...
(15 - x)2 = 81
(15 - x)2 = 92
15-x = 9
x = 15 - 9
=> x = 6