Simplify : 7x^2 + 6x + 9x^2 - 5x
1 answer:
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Answer:
E
Step-by-step explanation:
Given
y = 2x² - kx + 3
with a = 2, b = - k and c = 3
Since the curve touches the x- axis at one place then the roots are real and equal and the discriminant for this condition is
b² - 4ac = 0, that is
(- k)² - (4 × 2 × 3) = 0
k² - 24 = 0 ( add 24 to both sides )
k² = 24 ( take the square root of both sides )
k = ± = ± 2
k = 2 or k = - 2
→ E