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Evaluate 25^3/2, Giving Your Answer As A Integer (walk Through)
GCSE
Date : 24/03/2020
Question: Evaluate 253/2 giving your answer as an integer. (2 marks)
Basic understanding:
Evaluate just means " write this number in a different form/find the answer". In this case the base is the number (25 in the question) and the indices is the power (3/2 in the question).
First lets establish a2 = a x a.
Now, a1/2 = square-root(a). This is because a power of (1/2) is finding which number multiplied by itself twice makes the base (a), the literal reciprocal/opposite effect of an integer power of (2) which multiplies the base (a) by itself twice.
Please note you can also have power values of 3, 4 , 5 etc, or power values of 1/3, 1/4, 1/5 etc. They work in the same way as a power value of 2 or 1/2.
eg: a3 = a x a x a
eg2: a1/4 = fourth-root(a) [finds which number multiplied by itself four times gives base(a)]
Answer:
Step 1:
Break down the compound indices (power) to two parts, one is the numerator (integer power) and the other is the denominator (fractional power).
eg: 253/2 = 253 x 1/2.
Step 2:
Evaluate (either way) the two separated powers individually. Try priorities the option where you don`t have to work with larger numbers or decimals, the first option in the example below.
eg: 251/2 = 5 => 53 = 125 OR 253 = 15625 =>156251/2 = 125
125 if your final recorded answer.
This is an exemplar walk through so you get an idea on how I tutor. Please do remember this is only one simple way of tutoring this topic and if I had a student to interact with, I would take a different approach if a particular student struggled with any concept. Some students also may struggle learning by reading and are better vocal learners. Either way, I hope this is useful for most students at least.
This resource was uploaded by: Sal
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