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Solve the Quadratic Equation X2 - 3(X + 3) = 0; Give Your Answer Correct Two Significant Figures - Mathematics

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Question

Solve the quadratic equation x2 -  3(x + 3) = 0; Give your answer correct two significant figures

Solution

x2 -  3(x + 3) = 0

`=> x^2 - 3x - 9 = 0`

Comparing with `ax^2 + by + c` we get

`:. x = (-b+-sqrt(b^2 - 4ac))/(2a)`

`=> x = (-(-3)+- sqrt((-3)^2 - 4(1)(-9)))/(2(1))`

`=> x = (3+- sqrt(9+36))/2`

`=> x = (3+- sqrt45)/2`

`=> x = (3+- sqrt(9xx5))/2`

`=> x = (3+-3sqrt5)/2`

`=> x = (3+3sqrt5)/2 or x = (3-3sqrt5)/2`

`=> x  = (3+3xx2.236)/2 or x = (3-3xx2.236)/2`

`=> x = (3+6.708)/2 or x = (3-6.708)/2`

`=> x = 9.708/2 or x = (-3.708)/2`

`=>` x = 4.85 or x = -1.85

`=>` x = 4.9 or x = -1.9

  Is there an error in this question or solution?
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APPEARS IN

 Selina Solution for Concise Mathematics for Class 10 ICSE (2020 (Latest))
Chapter 5: Quadratic Equations
Exercise 5(D) | Q: 11 | Page no. 64
 2015-2016 (March) (with solutions)
Question 5.1 | 3.00 marks
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Solve the Quadratic Equation X2 - 3(X + 3) = 0; Give Your Answer Correct Two Significant Figures Concept: Quadratic Equations.
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