Question

4- If 3x + 4y = 12 and x y = 11, then find 9x2 + 16y2
5- If a2 + b2 = 10 and ab = 5, find the value of (a+ b)2​

Answer 1

Answer:

4- -120

5-. 20

Step-by-step explanation:

4- since, 3x+4y = 12

squaring both sides, and use formula of (A + B)2= A2 + B2 + 2AB

9x2+ 16y2 + 2*3x*4y = 144

9x2 + 16y2 + 24xy =144. (put xy = 11 given)

9x2 + 16y2 = 144 - 24*11 = 144 - 264 = -120

5-

since, (a + b)2 = a2 + b2 + 2ab

(a + b)2 = 10 + 2*5

= 10 + 10= 20

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