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प्रश्न
Choose the correct alternative answer for the following sub-questions and write the correct alphabet.
Which of the following quadratic equation has roots – 3 and – 5?
विकल्प
X2 – 8X + 15 = 0
X2 – 8X – 15 = 0
X2 + 8X + 15 = 0
X2 + 8X – 15 = 0
उत्तर
X2 + 8X + 15 = 0
Explanation:
The roots of the quadratic equation x2 + 8x + 15 = 0 are
x2 + 5x + 3x + 15 = 0 ....`((5 xx 3 = + 15),(5 + 3 = + 8))`
x(x + 5) + 3(x + 5) = 0
(x + 5)(x + 3) = 0
∴ x + 5 = 0
x = - 5
∴ x + 3 = 0
x = - 3
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