Question
Solve absolute value equation :
![2 vertical line x plus 8 vertical line equals 20](data:image/png;base64,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)
Hint:
|x| is known as the absolute value of x. It is the non-negative value of x irrespective of its sign. The value of absolute value of x is given by
![vertical line x vertical line equals open curly brackets table attributes columnalign right left right left right left right left right left right left columnspacing 0em 2em 0em 2em 0em 2em 0em 2em 0em 2em 0em end attributes row cell negative x comma x less than 0 end cell row cell x comma x greater or equal than 0 end cell end table close](data:image/png;base64,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)
So, we will get two cases in the solution of the given equation. We apply the given definition and then simplify the two equations to get the value of x.
The correct answer is: Hence, we get two values of x satisfying the given equation, x=2,-18
Step by step solution:
The given equation is
![2 vertical line x plus 8 vertical line equals 20](data:image/png;base64,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)
Using the definition of absolute value,
![vertical line x vertical line equals open curly brackets table attributes columnalign right left right left right left right left right left right left columnspacing 0em 2em 0em 2em 0em 2em 0em 2em 0em 2em 0em end attributes row cell negative x comma x less than 0 end cell row cell x comma x greater or equal than 0 end cell end table close](data:image/png;base64,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)
We get two possibilities,
For x + 8<0,
![2 vertical line x plus 8 vertical line equals negative 2 left parenthesis x plus 8 right parenthesis equals 20](data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAL8AAAASCAYAAAAKaA82AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAABGJhU0UAAAAOJ5y/mQAAAu9JREFUeNrtmkFkHFEYx0fUiooSVVU9lMghclihp4iqUNFDRIQcIqcIURXVe44VoioqqlRFD1UlIiKiSlRExFoioofeeuqhcukhIsYKyffZ/zId7719M7tv532b+fizM7PGN7/3vff+780EQbq4DOSFxJx18Zy05HF+S8ixLSMv/uyiSCoJyPMAuXofQ6R10impQjomTQsopJukFdIZKSR9J90XWPxJ+HNRDQjg/pC0nzGrW6T3pDL0Aef+iz3SFKkLx/2APOV5Ia2SFkk3SAVMt2WBxW/LfwDnpXDfRyfIghXHD9JY5HgU5+rGA9LPDAopyb3D2HEHRoN2sD0q/q9J84K4v2jR2kTFahKzUzzeGgZ140PWAzWredhXuNbsRjiLjAC1RvjTRp4/zp/txSNB3AdtR1oHrNgajSj+N4xrxhg0TLEmUEeku5HjGdI7RyPQCkaXaM5vUt730kKtDBX/U9gMKdwLyNk1bxWrfxpWfO7EdLNOeLihFKCekpbx+0mKnp/koYuYbivwgn81I6O0kV/H/0Ig94qHrLQ5dZM2NVOGLagd0mOsxG87GnHZ530h3Yv0cF5c/Q7UW2ytKP5mjGYm/hcCubss/rSslHa+BzfrbXCUeImHLqYsIJvY0NyfPd2uUNtTj7/J9vjI3aXtqcfqRMOqU2V7+kgfg+oebiOgavuwy7ar6pSNECa85rvtseG/Y7CiPnJ3teC1YbUOKxiPkfiClxdKa0F137YRUNwbt5AU7wYcWky/aRvhl6bX98ODSip+W/66rU5fuc8j5yxYTaCDxONTfHDYRm9qBNQd0rcYdH6p8NlRI0ygIYax1daB3+w9nwkrflv+qpdcPnN38ZIrSa3uwgrWXsYtYIFu7b9sQBXgBVWfFnzVTD/NCH6RcQSfG+LBxgXu9iThX4p4bp+5u/q8IQkrXhCvIsfzoPp5Q1czEpAW+YdtrQ0xH7blxS8r2F74/Ekz+/y5oE0jL/48rm2Eec55SI8rUs9Jr1LmOUAAAADndEVYdE1hdGhNTAA8bWF0aCB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMTk5OC9NYXRoL01hdGhNTCI+PG1uPjI8L21uPjxtbz58PC9tbz48bWk+eDwvbWk+PG1vPis8L21vPjxtbj44PC9tbj48bW8+fDwvbW8+PG1vPj08L21vPjxtbz4mI3gyMjEyOzwvbW8+PG1uPjI8L21uPjxtbz4oPC9tbz48bWk+eDwvbWk+PG1vPis8L21vPjxtbj44PC9tbj48bW8+KTwvbW8+PG1vPj08L21vPjxtbj4yMDwvbW4+PC9tYXRoPpBdDHoAAAAASUVORK5CYII=)
Simplifying, we get
-2x-16=20
Adding 16 both sides, we have
-2x=20+16=36
Dividing throughout by -2, we get
x = -18
For x + 8 ≥ 0,
![2 vertical line x plus 8 vertical line equals 2 left parenthesis x plus 8 right parenthesis equals 20](data:image/png;base64,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)
Simplifying, we get
2x +16 = 20
Subtracting 16 both sides, we get
2x = 20-16 = 4
Dividing by 2 throughout, we get
x = 2
Hence, we get two values of x satisfying the given equation,
x = 2, -18
Using the definition of absolute value,
We get two possibilities,
Simplifying, we get
Adding 16 both sides, we have
Dividing throughout by -2, we get
Simplifying, we get
Subtracting 16 both sides, we get
Dividing by 2 throughout, we get
Hence, we get two values of x satisfying the given equation,
Absolute value of a variable has many uses in mathematics. Geometrically, the absolute value of a number may be considered as
its distance from zero regardless of its direction. The symbol |.| is pronounced as ‘modulus’. We read |x| as ‘modulus of x’ or ‘mod x’.