Line CD passes through points C(1, 3) and D(4, –3). If the equation of the line is written in slope-intercept form, y = mx + b,
2 answers:
Answer:
b = 5
Step-by-step explanation:
Calculate m using the slope formula
m = (y₂ - y₁ ) / (x₂ - x₁ )
with (x₁, y₁ ) = C(1, 3) and (x₂, y₂ ) = D(4, - 3)
m = =
= - 2, hence
y = - 2x + b ← is the partial equation of the line
To find b substitute either of the 2 points into the partial equation
Using (1, 3), then
3 = - 2 + b ⇒ b = 3 + 2 = 5
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Answer:
(1, 8.5 ) and ( - 17, 80.5 )
Step-by-step explanation:
Given the 2 equations
y = x² + 4x + 4 → (1)
y = - 4x + 12 → (2)
Substitute (1) into (2), that is
x² + 4x + 4 = - 4x + 12
( multiply through by 2 to clear the fractions )
x² + 8x + 8 = - 8x + 25 ( add 8x to both sides )
x² + 16x + 8 = 25 ( subtract 25 from both sides )
x² + 16x - 17 = 0 ← in standard form
(x + 17)(x - 1) = 0 ← in factored form
Equate each factor to zero and solve for x
x + 17 = 0 ⇒ x = - 17
x - 1 = 0 ⇒ x = 1
Substitute these values into either of the 2 equations and evaluate for y
Substituting into (2 )
x = 1 : y = - 4(1) + 12.5 = - 4 + 12.5 = 8.5 ⇒ (1, 8.5 )
x = - 17 : y = - 4(- 17) + 12.5 = 68 + 12.5 = 80.5 ⇒ (- 17, 80.5 )