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91Ó°ÊÓ

Solve the equation by completing the square. Round to the nearest tenth.

2x2+4x−5=7

Short Answer

Expert verified

x=−3.6, 1.6are the solutions of the given equation.

Step by step solution

01

Step 1. Define the standard form of the quadratic equation.

A quadratic equation, which is written in the form, ax2+bx+c=0, where,a≠0 is called the standard form of the quadratic equation.

02

Step 2. Define the perfect square a+b2.

a+b2=a2+2ab+b2 â¶Ä‰â¶Ä‰â¶Ä‰â¶Ä‰â¶Ä‰â¶Ä‰â¶Ä‰â¶Ä‰â¶Ä‰â¶Ä‰...........1

03

Step 3. Solve the equation 2x2+4x−5=7 by completing the square.

Use (1) to solve the equation.

2x2+4x−5=72x2+4x=7+52x2+2x=12x2+2x=122x2+2x=6

x2+2x1=6x2+2x1+12=6+12x+12=6+1x+12=7x+1=±7x=−1±7

Use calculator.

x=−3.645751311, 1.645751311x≃−3.6, 1.6

Hence, x=−3.6, 1.6are the solutions of the given equation.

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