MCQ
If $x + y = 8$ and $xy = 15$, than $ x ^2 + y^2$
- A$32$
- B$1$
- ✓$34$
- D$36$
✓
Answer
Correct option: C.
$34$
$x^2 + y^2 = (x + y)^2 - 2xy$
$⇒ x^2 + y^2 = (8)^2 - 2 × 15$
$⇒ x^2 + y^2 = 64 - 30$
$⇒ x^2 + y^2 = 34$
$⇒ x^2 + y^2 = (8)^2 - 2 × 15$
$⇒ x^2 + y^2 = 64 - 30$
$⇒ x^2 + y^2 = 34$
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