Lesson 5 of 15
Always, or only sometimes
Show on a big screenTwo shops sell notebooks. Shop A charges 5n rupees for n notebooks. Shop B charges 2n + 3 rupees. For one notebook, both charge ₹5.
n = 1: 5n = 5. 2n + 3 = 5. Match! Step 1 of 3
n= 1:5n= 5.2n + 3= 5. Match!n= 2:5n= 10.2n + 3= 7. Apart.- One match is not proof.
Rule: two expressions are the same when they match at every value. One match proves nothing. One mismatch shows they are different.
Both n + n and 2n mean two lots of n. So they match at every value.
Pick a pair. Tap to try n = 1, 2 and on.
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Try the lab to finish this lesson.