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If (2m + 3n) = 3 and mn = 1, what is the value of 4m2 + 9n2? 1.-3 2.-2 3.-4 4.-5
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Step-by-step explanation:
(2m + 3n) = 3
mn = 1
let 2m = a and 3m = b
therefore,
2m + 3n = a + b = 3 ---> (i)
ab = (2m×3n) = 6mn = 6(1) --->(ii)
4m² = a² and 9n² = b²
therefore,
4m² + 9n² = a²+b² = (a + b)² - 2ab ---> (iii)
substituting equations (I) & (ii) in equation (iii), we get,
4m²+9n²=(a+b)²-2ab= (3)²-2(6)=9-12= -3
therefore, 4m²-9n²= -3
Hope this helps
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