Question

3. If x-y=7 and xy=9, then the value of
(x²+ y2) is:
a) 64
O b) 67
O c) 63
O d) 52​

Answer 1

$(x - y) {}^{2} = 7 {}^{2}$

$x {}^{2} + y {}^{2} - 2xy = 49$

$x {}^{2} + y {}^{2} - 2 \times 9 = 49$

$x {}^{2} + y {}^{2} = 49 + 18$

$x {}^{2} + y {}^{2} = 67$

option b (67)

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