Question

solve quadratic equation using quadratic formula
1.x²+8x+15=0
2. 2x²- x=0
3. x² - 2x -10=0​

Answer 1

Answer:

x

2

+8x+15=0

x

2

+8x=−15

x

2

+8x+16=−15+16

x

2

+2×4x+4

2

=1

(x+4)

2

=1

x+4=±1

Hence, x=−4+1=−3 or x=−4−1=−5

Step-by-step explanation:

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Answer 2

Question:-

solve quadratic equation using quadratic formula

1.x²+8x + 15 = 0

2. 2x²- x=0

3. x² - 2x -10=0

Solution:-

1.

x² + 8x + 15 = 0

a = 1 ; b = 8 ; c = 15

➭ -b ± √b² - 4ac

2a

➭ -8 ± √8² - 4(1)(15)

2(1)

➭ -8 ± √64 - 60

2

➭ -8 ± √4

2

➭ -8 - 2 and -8 + 2

2 2

➭ -10/2 and -6/2

➭ -5 and -3

2.

2x² - x = 0

a = 2 ; b = -1 ; c = 0

- (-1) ± √-1² - 4(2)(0)

2(2)

1 ± √1 - 0

4

1 + 1 and 1 - 1

4 4

2/4 and 0

1/2 ; 0

3.

x² - 2x - 10 = 0

a = 1 ; b = -2 ; c = -10

➭ - (-2) ± √-2² - 4(1)(-10)

2(1)

➭ 2 ± √4 +40

2

➭ 2 ± √ 44

2

➭ 2 + √44 and 2 - √44

2 2

Verification:-

➭ 2x² - x = 0

➭ 2(1/2) - 1/2 = 0

➭ 1 - 1/2 = 0

➭ 2/2 - 1/2 = 0

➭ 1/2 ≠ 0

➭ x = 0

➭ 2(0)² - 0 = 0

➭ 0 = 0