Please help me please will give brainliest

do only 23 ,25,

by factoring

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  23)  x = ±3i, ±√2

  26)  x = 4/3, (-2/3)(1 ± i√3)

Step-by-step explanation:

23) Put in standard form to make factoring easier.

  x^4 +7x^2 -18 = 0

  (x^2 +9)(x^2 -2) = 0 . . . . factors in integers

Using the factoring of the difference of squares, you can continue to get linear factors in complex and irrational numbers:

  (x -3i)(x +3i)(x -√2)(x +√2) = 0

  x = ±3i, ±√2

___

26) This will be the difference of cubes after you remove the common factor.

  81x^3 -192 = 0

  3(27x^3 -64) = 0

  (3x -4)(9x^2 +12x +16) = 0 . . . . . factor the difference of cubes

The complex roots of the quadratic can be found using the quadratic formula.

  x = (-12 ±√(12^2 -4(9)(16)))/(2(9)) = (-12 ±√-432)/18 = -2/3 ± √(-4/3)

Then the three solutions to the equation are ...

  x = 4/3, (-2/3)(1 ± i√3)

4.6875 pounds

step-by-step explanation: