Question

An equation in the form ax2+bx+c=0 is solved by the quadratic formula. The solution to the equation is shown below.x=−7±√ "572" What are the values of a, b, and c in the quadratic equation?
A: a= 1, b= -7, c = -2
B: a = 1, b= 7, c = -2
C: a = 2, b = -7, c = -1
D: a = 2, b = 7, c = -1

Answer 1

Let's see

• x=-b±√b²-4ac/2a

On comparing

• -b=-7
• b=7

And

• 2a=2
• a=2/2
• a=1

So

• b²-4ac=57
• 7²-4c=57
• 4c=49-57
• 4c=-8
• c=-2

Option B

Answer 2

Answer:

B: a = 1, b= 7, c = -2

Explanation:

$\sf Quadratic \ Equation : \dfrac{-b\pm \sqrt{b^2 - 4ac} }{2a}$

Knowing This:

solve for b

• -b = -7

• b = 7

solve for a:

• 2a = 2

• a = 1

solve c:

• b² - 4ac = 57

• 7² - 4(1)(c) = 57

• -4c = 57 - 49

• -4c = 8

• c = 8/-4 = -2