Question Video: Finding the Value of an Unknown by Factorizing the Difference of two Squares Mathematics • 9th Grade

If π₯Β² β π = (π₯ + 5)(π₯ β 5), what is the value of π?

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Video Transcript

If π₯ squared minus π equals π₯ plus five times π₯ minus five, what is the value of π?

Hereβs what we know. We know that π₯ squared minus π is going to equal π₯ plus five times π₯ minus five. But to find out what the π value is, weβll need to multiply out π₯ plus five and π₯ minus five.

Starting with our first term, weβll multiply π₯ times π₯ equals π₯ squared. π₯ times negative five equals negative five π₯. Five times π₯ equals five π₯. Five times negative five equals negative 25. We can bring down the first part of our problem: π₯ squared minus π.

I wanna us to look closely at these two middle terms. They say negative five π₯ or minus five π₯ plus five π₯. What is five π₯ minus five π₯? Negative five π₯ plus five π₯ equals zero. Those two middle terms drop out. They cancel each other out. π₯ squared minus π equals π₯ squared plus zero minus 25. Or in completely simplified terms, π₯ squared minus π equals π₯ squared minus 25. So we know for sure our π value is 25.