Preview: Understand Algebraic Substitution with Squares and Square Roots
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Introduction
When we substitute a number for a letter, we simply replace the letter with the number.
However, we must remember that 4b means 4 × b and 4b2 means 4 × b × b.
Example
Work out the value of the following expression when a = 4 and b = 9
3a2 - 7 - 2√b
Answer
3a2 - 7 - 2√b
= 3 × a × a - 7 - 2 × √b
= 3 × 4 × 4 - 7 - 2 × √9
= 48 - 7 - 2 × 3
= 48 - 7 - 6
= 35
Let's try some questions now. Remember that you can check back to this introduction at any point by clicking on the red button at the side of the screen.
When we substitute a number for a letter, we simply replace the letter with the number.
However, we must remember that 4b means 4 × b and 4b2 means 4 × b × b.
Example
Work out the value of the following expression when a = 4 and b = 9
3a2 - 7 - 2√b
Answer
3a2 - 7 - 2√b
= 3 × a × a - 7 - 2 × √b
= 3 × 4 × 4 - 7 - 2 × √9
= 48 - 7 - 2 × 3
= 48 - 7 - 6
= 35
Let's try some questions now. Remember that you can check back to this introduction at any point by clicking on the red button at the side of the screen.
Question
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