Question

If A={x²+y²=16} and B={9x²+25y²=225}• Then n(A intersection B) is equal to

Answer 1

Step-by-step explanation:

9x²+25y² = 225 (1)

x²+y² = 16 (2)

multiply (2) by -9

-9x²-9y² = -144 (3)

add (1) and (3)

9x²+25y² = 225

-9x²-9y² = -144

----------------------

16y² = 81

y² = 81/16

substitute y² = 81/16 in (2)

x² + 81/16 = 16

x² = 16 - 81/16

x² = (256 - 81) /16

x² = 175/16

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