# Which constant must be added and subtracted to solve the quadratic equation 9x2+34x-2 = 0 by the method of completing the square? - Mathematics

MCQ

Which constant must be added and subtracted to solve the quadratic equation 9x^2 + 3/4x - sqrt(2) = 0 by the method of completing the square?

• 1/8

• 1/64

• 1/4

• 9/64

#### Solution

1/64

Explanation:

Given equation is 9x^2 + 3/4x - sqrt(2) = 0

(3x)^2 + 1/4 (3x) - sqrt(2) = 0

On putting 3x = y

We have y^2 + 1/4y - sqrt(2) = 0

y^2 + 1/4y + (1/8)^2 - (1/8)^2 - sqrt(2) = 0

(y + 1/8)^2 = 1/64  + sqrt(2)

(y + 1/8)^2 = (1 + 64 sqrt(2))/64

Thus, 1/64 must be added and subtracted to solve the given equation.

Concept: Nature of Roots of a Quadratic Equation
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#### APPEARS IN

NCERT Mathematics Exemplar Class 10