Question

solve the given quadratic equation by completing square method. x^ + x- 20 =0​

Answer 1

Answer:

x = -5 or x = 4

Step-by-step explanation:

=> x^2 + x - 20 = 0

• Divide by the coefficient of x^2

=> (x^2 + x - 20)/1 = 0/1

=> x^2 + x - 20 = 0

=> x^2 + 2(x/2) - 20 = 0

• Add and subtract the square of the coefficient of 2x i.e. 1/2

=> x^2 + 2(x/2) + (1/2)² - (1/2)² - 20 = 0

=> (x + 1/2)² = 20 + 1/4

=> (x + 1/2)² = 81/4

=> x + 1/2 = ± 9/2

=> x = 4 or - 5

Answer 2

Step-by-step explanation:

$x + 2 \times x 1 \2 + (1 \2) = 20 + (1 \2) \: \: \: \: \: \: \: \: \: \: \: (x + 1 \2) = 20 + 1 \4 \\ \\ \\ \\ (x + 1 \2 = 80 + 1 \4 \\ \\ \\ \\ \ \\ (x + 1 \2) = 81 \4 \\ \\ \\ \\ \\ (x + 1 \2 = + 9 \2 \\ \\ \\ \\ \\ x = - 1 \2 + 9 \2 \\ \\ \\ \\ \\ \\ \\ x = ( - 1 \2 + 9 \2) or \\ \\ \\ \\ \\ x = ( - 1 \2 - 9 \2) \\ \\ \\ \\ \\ x = 8 \2 \: or \\ - 10 \2 \\ \\ \\ x = 4 \\ or \\ x = - 5$