SOLUTION: If three times the square of a negative number is added to the product of -7 and the number the result is 20. Find the number.

Question 307202: If three times the square of a negative number is added to the product of -7 and the number the result is 20. Find the number.
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
The phrase "three times the square of a negative number is added to the product of -7 and the number the result is 20." translates to where 'x' is a negative number.

Start with the given equation.

Subtract 20 from both sides.

Notice that the quadratic is in the form of where , , and

Let's use the quadratic formula to solve for "x":

Start with the quadratic formula

Plug in , , and

Negate to get .

Square to get .

Multiply to get

Rewrite as

Add to to get

Multiply and to get .

Take the square root of to get .

or Break up the expression.

or Combine like terms.

or Simplify.

So the possible solutions are or

Keep in mind that 'x' is a negative number. So the only answer is

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