a ) ( x - 5 * 9 ) * 2 = 0
b ) 40 * ( x - 2 ) = 40
c ) ( x - 4 ) * 3 + 2 = 101
Dấu * là dấu nhân nha mọi người
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
\(\left(x-9\right)^3.\left(x^2-4\right)-x^2=-4\)
Đầu bài thế này hả bạn??
\(1,\\ a,\Rightarrow x=\dfrac{5\cdot4}{3}=\dfrac{20}{3}\\ b,\Rightarrow x=8\\ c,\Rightarrow x=\dfrac{27\cdot2}{3,6}=15\\ 2,\\ a,\dfrac{6}{9}=\dfrac{42}{63};\dfrac{6}{42}=\dfrac{9}{63};\dfrac{63}{9}=\dfrac{42}{6};\dfrac{63}{42}=\dfrac{9}{6}\\ b,\dfrac{4}{18}=\dfrac{2}{9};\dfrac{4}{2}=\dfrac{18}{9};\dfrac{9}{18}=\dfrac{2}{4};\dfrac{9}{2}=\dfrac{18}{4}\)
a) \(\left(x^2-9\right)\cdot\left(4^x-16\right)=0\)
\(\Rightarrow x^2-9=0\)hoặc \(4^x-16=0\)
\(x^2=9\) \(4^x=16\)
\(x^2=\left(\pm3\right)^2\) \(4^x=4^2\)
\(\Rightarrow x=\pm3\)hoặc \(x=2\)
b) \(5^x+5^{x+2}=650\)
\(\Rightarrow5^x+5^x\cdot25=650\)
\(\Rightarrow5^x\cdot\left(1+25\right)=650\)
\(\Rightarrow5^x\cdot26=650\)
\(\Rightarrow5^x=650\div26=25\)
\(\Rightarrow5^x=5^2\)
\(\Rightarrow x=2\)Vậy \(x=2\)
c) \(2^{x+2}-2^x=96\)
\(2^x\cdot4-2^x=96\)
\(2^x\cdot\left(4-1\right)=96\)
\(2^x\cdot3=96\)
\(2^x=96\div3=32\)
\(2^x=2^5\)Vậy \(x=5\)
a. 12,5 - \(x\) = \(x\) + 12
\(x\) + 12 + \(x\) = 12,5
\(x\) x 1 + \(x\) x 1 = 12,5 - 12
\(x\) x (1 + 1) = 0,5
\(x\) x 2 = 0,5
\(x\) = 0,5 : 2
\(x\) = 0,25
b, 8 \(\times\) \(x\) + 3 \(\times\) \(x\) + 2 \(\times\) \(x\) = 20
\(x\) \(\times\) (8 + 3 + 2) =20
\(x\) \(\times\) 13 = 20
\(x\) = 20 : 13
\(x\) = \(\dfrac{20}{13}\)
A) 7/38 x 9/11 +7/38 x 4/11 -7/38 x 2/11
=7/38.(9/11+4/11-2/11)
=7/38
B) 5/31 x 21/25 + 5/31 x -7/10 - 5/31 x 9/20
=5/31.(21/25-7/10-9/20)
=5/31.(-31/100)
=-1/20
`a)4/5:3/x xx2/11=24/165`
`(4/5xx2/11)xx 3/x=8/55`
`8/55xx3/x=8/55`
`3/x=8/55:8/55`
`3/x=1`
`3:x=1`
`x=3:1`
`x=3`
____________________________________________
`b)4/3:x/5=5/13xx4/9`
`4/3:x/5=20/117`
`x/5=4/3:20/117`
`x/5=39/5`
`x=39`
A) 4/5:3/x X 2/11=24/165
\(\dfrac{4}{5}:\dfrac{3}{x}X\dfrac{2}{11}=\dfrac{24}{165}\)
\(\dfrac{3}{x}=\dfrac{24}{165}:\dfrac{4}{5}:\dfrac{2}{11}\)
\(\dfrac{3}{x}=1\)
\(\dfrac{3}{x}=\dfrac{3}{3}\)
=> x=3
B) \(\dfrac{4}{3}:\dfrac{x}{5}=\dfrac{5}{13}x\dfrac{4}{9}\)
\(\dfrac{4}{3}:\dfrac{x}{5}=\dfrac{20}{117}\)
\(\dfrac{x}{5}=\dfrac{4}{3}:\dfrac{20}{117}\)
\(\dfrac{x}{5}=\dfrac{39}{5}\)
=> x = 39
Bạn chú thích hơi quá lố :)
Ta có :( 5x - 3y + 4z ) . ( 5x - 3y - 4z ) \(=\left(5x-3y\right)^2-16z^2\)
\(=25x^2-30xy+9y^2-16z^2\)
Mà x^2=y^2 + z^2 nên ( 5x - 3y + 4z ) . ( 5x - 3y - 4z )\(=25x^2-30xy+9y^2-16\left(x^2-y^2\right)\)
\(=9x^2-30xy+25y^2=\left(3x-5y\right)^2\)
Học tốt !
Bài giải
a, \(\left(x-5\cdot9\right)\cdot2=0\)
\(x-45=0\)
\(x=45\)
b, \(40\cdot\left(x-2\right)=40\)
\(x-2=1\)
\(x=3\)
c, \(\left(x-4\right)\cdot3+2=101\)
\(\left(x-4\right)\cdot3=99\)
\(x-4=33\)
\(x=37\)
Bài làm :
\(a,\left(x-5.9\right).2=0\)
\(\Rightarrow x-45=0\)
\(\Rightarrow x=0+45\)
\(\Rightarrow x=45\)
\(b,40.\left(x-2\right)=40\)
\(\Rightarrow x-2=40:40\)
\(\Rightarrow x-2=1\)
\(\Rightarrow x=3\)
\(c,\left(x-4\right).3+2=101\)
\(\Rightarrow\left(x-4\right).3=99\)
\(\Rightarrow x-4=99:3\)
\(\Rightarrow x-4=33\)
\(\Rightarrow x=37\)
Học tốt nhé