Question

Solve for x

15x^2+16x= -4

Answer 1

15x² + 16x = -4
15x² + 16x + 4 = -4 + 4
15x² + 16x + 4 = 0
x = -(16) +/- √((16)² - 4(15)(4))
2(15)
x = -16 +/- √(256 - 240)
30
x = -16 +/- √(16)
30
x = -16 +/- 4
30
x = -8 +/- 2
15
x = -8 + 2 or x = -8 - 2
15 15
x = -6 x = -10
15 15
x = ⁻²/₅ x = ⁻²/₃

Answer 2

15x²+16x+4 =0 (ax² +bx +c=0)

Δ = b²-4ac =256 - 4×15×4 =16

x1 = (-b+√Δ) / 2a = (-16+√16) / 30 =( -16+4) / 30 = -12/30 = - 2/5
x2 = (-b -√Δ) / 2a = (-16 -√16) / 30 = (-16 -4) /30 = -20/30 = -2/3