f.3 MATHS! QUICK HELP PLS !!!!

1.
(aᵐ - bᶜ)/aⁿ ≠ aᵐ⁻ⁿ - bᶜ

Since (u - v)/w =(u/w) - (v/w), then

(aᵐ - bᶜ)/aⁿ
= (aᵐ/ aⁿ) -(bᶜ/aⁿ)
= aᵐ⁻ⁿ - (bᶜ/aⁿ)
≠ aᵐ⁻ⁿ - bᶜ


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2.
Since (1/4)x²ᵐ⁺ⁿyⁿ⁺² and -3xᵐ⁺³y⁷, then

2m + n = m + 3 ...... [1]
n + 2 = 7 ...... [2]

From [2] :
n = 5

Put n = 5 into [1] :
2m + 5 = m + 3
m = -2

Hence, m = -2, n = 5

2014-09-24 23:18:43 補充：
2. The first line should be :
"Since (1/4)x²ᵐ⁺ⁿyⁿ⁺² and -3xᵐ⁺³y⁷ are like terms, then"

2014-09-24 23:19:33 補充：
若有新題目，請開新發問，不要再加在「補充」中。

2014-09-26 03:25:46 補充：
The coefficients of like terms can be differ from each other.