Answer:
x = -4 ±√(7)
or in decimal:
x = -1.35 or -6.65
Step-by-step explanation:
y=x²+8x+9
note x-intercepts occur when y = 0,
Hence, x²+8x+9 = 0 (solve this using your favorite method. We will complete the square)
x²+8x+9 = 0 (rearrange)
x²+8x = -9 (complete the square and add factor to both sides)
x² + 8x + (8/2)² = -9 + (8/2)²
[ x + (8/2) ]² = -9 + (8/2)²
[ x + 4 ]² = -9 + (4)²
[ x + 4 ]² = -9 + 16
[ x + 4 ]² = 7
x+4 = ±√(7)
x = -4 ±√(7)
x = -1.35 or -6.65
