Question

Solve the quadratic equation 3x^2 – 5x – 7 = 0
Give your answers to 3 significant figures.

Answer 1

2.57 or -0.907

Explanation:

→ First state the quadratic formula

`\frac{-b+-\sqrt{b^(2)-4ac } }{2a}`

→ Identify the 'a', 'b' and 'c' variables

`ax^(2) +bx+c`

`3x^(2) -5x-7`

a = 3, b = -5 and c = -7

→ Substitute in the values into the quadratic formula

`\frac{5+\sqrt{5^(2)-4*3*-7 } }{2*3}=(5+√(25+84 ) )/(6)=(5+√(109 ) )/(6)=2.573384418`

→ Do the same for negative

`\frac{5-\sqrt{5^(2)-4*3*-7 } }{2*3}=(5-√(25+84 ) )/(6)=(5-√(109 ) )/(6)=-0.9067177515`