For x² + 11x + 28 = 0, Ishan writes x = −11 ± √(121 − 112)/2 and reports the roots −11 ± 1.5. Which correction does he need?

Question

Accepted Answer

The whole numerator −11 ± 3 must be divided by 2, giving −4 and −7. The bar in the formula runs under the entire numerator, not just the square root: x = -11 ± √121 - 1122 = -11 ± 3/2 = −4 or −7. Ishan's values −9.5 and −12.5 fail the check, while x = −4 gives 16 − 44 + 28 = 0 and x = −7 gives 49 − 77 + 28 = 0.

For $x^{2} + 11 x + 28 = 0$ , Ishan writes $x = - 11$ ± √(121 − 112)/2 and reports the roots −11 ± 1.5.
Which correction does he need?

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More Class 10 The Quadratic Formula practice

For x2+11x+28=0, Ishan writes x=−11 ± √(121 − 112)/2 and reports the roots −11 ± 1.5.Which correction does he need?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 10 The Quadratic Formula practice

For $x^{2} + 11 x + 28 = 0$ , Ishan writes $x = - 11$ ± √(121 − 112)/2 and reports the roots −11 ± 1.5.
Which correction does he need?