Question

If a²+b²=9 and ab=4 find the value of 3(a+b)²-2(a-b)²

Answer 1

(a+b)²=a²+b²+2ab= 9+2*4=17
(a-b)²=a²+b²-2ab=9-2*4=1
putting both values in eq.
3*17-2*1=49

Answer 2

Step-by-step explanation:

a ²+ b² =9

ab= 4

(a+b)²=a²+b²+2.a.b

=> 9+2×4

=>17

(a-b)² = a²+b²-2.a.b

=> 9-2×4

=> 1

3(a+b)² - 2(a-b)²

=>3×17 - 2×1

=>51 - 2

=> 49

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