Question Video: Evaluating Algebraic Expressions by Direct Substitution | Nagwa Question Video: Evaluating Algebraic Expressions by Direct Substitution | Nagwa

# Question Video: Evaluating Algebraic Expressions by Direct Substitution Mathematics • First Year of Preparatory School

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Evaluate 𝑦²− 4 + 3 if 𝑦 ₌ 6.

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### Video Transcript

Evaluate 𝑦 squared minus four plus three if 𝑦 equals six.

Even though this expression has three different operations, we always start with the same procedure. I’m sure you guessed copy down the expression. And if you did, you would be right; that’s the first thing we need to do. Next, we’re gonna replace 𝑦 with six because that was our given value. As you solve more and more complicated expressions, the most important thing you can remember is that you have to follow the order of operations.

We have correctly substituted the six for the 𝑦. But now, what operation comes first? Since we don’t have any parentheses or brackets in this problem, order of operations would tell us to go ahead and solve your exponents next. So, I’ve solved for six squared which equals 36 and copied the rest of the problem down. Following order of operations, I now need to add and subtract from left to right. In this step, I subtracted four from 36. And our next order of operations step will be to add 32 plus three. Our final answer for this expression when 𝑦 equals six, 𝑦 squared minus four plus three equals 35.

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