Tính nhanh
A 60-13.75-26.25
B 0.25x 611.7x40
C 6.28x18.24+18.24x3.72
D 36.4x99+36+0.4
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a) \(x^2-36=0\)
\(\Rightarrow x^2-6^2=0\)
\(\Rightarrow\left(x-6\right)\left(x+6\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-6=0\\x+6=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\)
b) \(x^3-0,25x=0\)
\(\Rightarrow x\left(x^2-0,25\right)=0\)
\(\Rightarrow x\left[x^2-\left(0,5\right)^2\right]=0\)
\(\Rightarrow x\left(x-0,5\right)\left(x+0,5\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x-0,5=0\\x+0,5=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=0,5\\x=-0,5\end{matrix}\right.\)
c) \(x^2-10x=-25\)
\(\Rightarrow x^2-10x+25=0\)
\(\Rightarrow x^2-2\cdot x\cdot5+5^2=0\)
\(\Rightarrow\left(x-5\right)^2=0\)
\(\Rightarrow x-5=0\)
\(\Rightarrow x=5\)
d) \(x^2-2x=-1\) (sửa đề)
\(\Rightarrow x^2-2x+1=0\)
\(\Rightarrow\left(x-1\right)^2=0\)
\(\Rightarrow x-1=0\)
\(\Rightarrow x=1\)
e) \(x^3+3x^2=-3x-1\)
\(\Rightarrow x^3+3x^2+3x+1=0\)
\(\Rightarrow\left(x+1\right)^3=0\)
\(\Rightarrow x+1=0\)
\(\Rightarrow x=-1\)
\(\text{#}Toru\)
a: \(x^2-36=0\)
=>\(x^2=36=6^2\)
=>\(\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\)
b: \(x^3-0,25x=0\)
=>\(x\left(x^2-0,25\right)=0\)
=>\(x\left(x-0,5\right)\left(x+0,5\right)=0\)
=>\(\left[{}\begin{matrix}x=0\\x-0,5=0\\x+0,5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=0,5\\x=-0,5\end{matrix}\right.\)
c: \(x^2-10x=-25\)
=>\(x^2-10x+25=0\)
=>\(\left(x-5\right)^2=0\)
=>x-5=0
=>x=5
e: \(x^3+3x^2=-3x-1\)
=>\(x^3+3x^2+3x+1=0\)
=>\(\left(x+1\right)^3=0\)
=>x+1=0
=>x=-1
Bài 2:
a: =>x-35=-23
=>x=12
b: =>|x-8|=13
=>x-8=13 hoặc x-8=-13
=>x=21 hoặc x=-5
Bài 1:
a: =42-98-42+12-12=-98
b: =10x4x3x(-25)=40x(-25)x3=-1000x3=-3000
\(a,=\left(73-27\right)\left(73^2+73\cdot27+27^2\right)=46\cdot8029=369334\\ b,=\left(63-27\right)\left(63+27\right)+\left(72-18\right)\left(72+18\right)\\ =100\cdot36+54\cdot100=100\left(36+54\right)=100\cdot90=9000\\ c,=\left(105-5\right)^3=100^3=1000000\)
Bài 4:
\(x^3-2x^2+x=x\left(x-1\right)^2\)
\(5\left(x-y\right)-y\left(x-y\right)=\left(x-y\right)\left(5-y\right)\)
\(x^2-12x+36=\left(x-6\right)^2\)
36,4 x 9 + 36 + 0,4
= 36,4 x 9 + ( 36 + 0,4 )
= 36,4 x 9 + 36,4
= 36,4 x ( 9 + 1 )
= 36,4 x 10
= 364
\(12371-5428+1429=\left(12371+1429\right)-5428=13800-5428=8372\\ 36,44\times99+36+0,4=36,4\times\left(100-1\right)+\left(36+0,4\right)=36,4\times100-36,4+36,4=3640+0=3640\)
13.75 + 23.13 - 120
= 13.(75 + 23) - 120
= 13.98 - 120
= 1274 - 120
= 1154
60- 13.75- 26.25
= 60- (13,75+26,25)
= 60- 40
= 20
0.25x 611.7x40
= 0,25x 40x 611
= 10x 611
= 6110
6.28x 18.24+18.24x 3.72
= 18,24 x (6,28+3,72)
=18,24 x 10
= 182,4
a,60-13,75-26,25
=60-(13,75+26,25)
=60-40
=20
b,0,25x 611,7x40
=611,7x(0,25x40)
=611,7x10
=6117
c,6,28x18,24+18.24x3,72
=18,24x(6,28+3,72)
=18,24x10
=184,4
d,36,4x99+36+0,4
=36,4x99+36,4
=3640