Five less than twice the square of a negative number is -9 times the number. Find the number.
1 answer:
Since the first part says the value is five less then twice the square of a negative number we get the first equation as 2(-x)²-5. Then we have that -9x is equal to that previous equation. Therefore our new equation is 2(-x)²-5=-9x. We can move the nine over by adding it to both side to get 2(-x)²+9x-5=0. Then you can use any method of factoring (I prefer quadratic formula) to get your values for x. By doing so, you’ll get x=28 and x=-32.5. Since the problem said the number was negative in the first part, you know you can’t have the 28 as the answer so the right answer is -32.5.
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