Question

Formúla General
a) 4x²=9x-2=0

b) X²+8x-84=0
​

Answer 1

Answer: a)
`x=(-9 \pm√(113) )/(8)`

b) x₁ = - 14; x₂ = 6.

Explanation:

a) 4x² + 9x - 2 = 0

`x=\frac{-b \pm \sqrt{b^(2)-4ac } }{2a} \\\\a=4; \: \: b=9; \: \: c=-2\\x =\frac{-9 \pm \sqrt{9^(2)-4 \cdot 4 \cdot (-2) } }{2 \cdot 4} =(-9 \pm√(113) )/(8)`

b) x² + 8x - 84 = 0

`x=\frac{-b \pm \sqrt{b^(2)-4ac } }{2a} \\\\a=1; \: \: b=8; \: \: c=-84\\\\x =\frac{-8 \pm \sqrt{8^(2)-4 \cdot 1 \cdot (-84) } }{2 \cdot 1} =(-8 \pm√(400) )/(2)=(-8 \pm 20)/(2) =-4 \pm 10\\\\x_(1) =-14\\x_(2) =6`