Bài 2:
a: xy=-21
=>(x;y)∈{(1;-21);(-21;1);(-1;21);(21;-1);(3;-7);(-7;3);(-3;7);(7;-3)}
b: xy-3=-6
=>xy=-6+3=-3
=>(x;y)∈{(1;-3);(-3;1);(-1;3);(3;-1)}
c: (x-1)*x+2=7
=>\(x^2-x-5=0\)
=>\(x^2-x+\frac14-\frac{21}{4}=0\)
=>\(\left(x-\frac12\right)^2=\frac{21}{4}\)
=>\(x-\frac12=\pm\frac{\sqrt{21}}{2}\)
=>\(x=\frac{1\pm\sqrt{21}}{2}\)
d: (2x-1)(2y+1)=-35
=>(2x-1;2y+1)∈{(1;-35);(-35;1);(-1;35);(35;-1);(5;-7);(-7;5);(-5;7);(7;-5)}
=>(2x;2y)∈{(2;-36);(-34;0);(0;34);(36;-2);(6;-8);(-6;4);(-4;6);(8;-6)}
=>(x;y)∈{(1;-18);(-17;0);(0;17);(18;-1);(3;-4);(-3;2);(-2;3);(4;-3)}
Bài 1:
a: x+x+x+82=-2-8
=>3x=-10-82=-92
=>\(x=-\frac{92}{3}\)
b: \(5\cdot\left(-4\right)\cdot x=-100\)
=>\(x\cdot\left(-20\right)=-100\)
=>\(x=\frac{-100}{-20}=5\)
c: \(\left(-1\right)\cdot\left(-3\right)\cdot\left(-6\right)\cdot x=36\)
=>-18x=36
=>\(x=\frac{36}{-18}=-2\)
d: \(-151-\left(3x+1\right)=\left(-2\right)\cdot\left(-7\right)\)
=>-151-3x-1=14
=>-152-3x=14
=>3x=-152-14=-166
=>\(x=-\frac{166}{3}\)
Bài 1 :
a , x + x + x + 82 = -2 -8 b ,5 . (-4) . x = 100
3x + 82 = -10 -20 . x = 100
3x = -92 x = -5
x = \(\frac{-92}{3}\) Vậy x = -5
Vậy x = \(\frac{-92}{3}\)
c , (-1 ) . (-3) . (-6) . x = 36 d , -151 - ( 3 . x + 1 ) = (-2) . (-7)
-18 . x = 36 -151 - ( 3x + 1 ) = 14
x = -2 -( 3x + 1 ) = 165
Vậy x = -2 3x + 1 = -165
3x = -166
x = \(\frac{-166}{3}\)
Vậy x = \(\frac{-166}{3}\)
Bài 2 : mik ko bt làm
Bài 1 :
a , x + x + x + 82 = -2 -8
3x + 82 = -10
3x = -92
x = \(\frac{- 92}{3}\)
Vậy x = \(\frac{- 92}{3}\)
b ,5 . (-4) . x = 100
-20 . x = 100
x = -5
Vậy x = -5
c , (-1 ) . (-3) . (-6) . x = 36
-18 . x = 36
x = -2
Vậy x = -2
d , -151 - ( 3 . x + 1 ) = (-2) . (-7)
-151 - ( 3x + 1 ) = 14
-( 3x + 1 ) = 165
3x + 1 = -165
3x = -166
x = \(\frac{- 166}{3}\)
Vậy x = \(\frac{- 166}{3}\)
Bài 2 : mik ko bt làm
