Chapter 9: Q. 96 E (page 885)

Solve quadratic equations of the form $x^{2} + b x + c = 0$ by completing the square.
In the following exercises , solve by completing the square.
$(y + 9) (y + 7) = 80$

Short Answer

Expert verified

The required value of $y$ is $1, - 17$

Step by step solution

Given information

$(y + 9) (y + 7) = 80$

Calculation

$(y + 9) (y + 7) = 80 \Rightarrow y (y + 7) + 9 (y + 7) = 80 \Rightarrow y^{2} + 7 y + 9 y + 63 = 80 \Rightarrow y^{2} + 16 y = 80 - 63 \Rightarrow y^{2} + 16 y = 17 \Rightarrow y^{2} + 16 y + {(\frac{1}{2} \times 16)}^{2} = 17 \Rightarrow y^{2} + 16 y + 64 = 17 + 64 \Rightarrow {(y + 8)}^{2} = 81 \Rightarrow y + 8 = \pm \sqrt{81} = \pm 9 \Rightarrow y = - 8 \pm 9 = - 8 + 9, - 8 - 9 = 1, - 17$

The required value of $y$ is $1, - 17$

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Solve quadratic equations of the form $x^{2} + b x + c = 0$ by completing the square.
In the following exercises , solve by completing the square.
$(y + 9) (y + 7) = 80$

Short Answer

Step by step solution

Given information

Calculation

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Solve quadratic equations of the form x2+bx+c=0by completing the square.In the following exercises , solve by completing the square.(y+9)(y+7)=80

Short Answer

Step by step solution

Given information

Calculation

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Math Textbooks

Calculus

Mechanics Maths

Theoretical and Mathematical Physics

Geometry

Probability and Statistics

Applied Mathematics

Study anywhere. Anytime. Across all devices.

Solve quadratic equations of the form $x^{2} + b x + c = 0$ by completing the square.
In the following exercises , solve by completing the square.
$(y + 9) (y + 7) = 80$