y = -1.5; y = x^2 + 8x + a; In the given system of equations, a is a positive constant. The system..

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Bluebook Digital SAT Test 4 Module 2 (Hard) Question 16:

y = -1.5
y = x^2 + 8x + a

In the given system of equations, a is a positive constant. The system has exactly one distinct real solution. What is the value of a?

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Thank you for the very clear explanations!
A faster way for those scared about the time is to plug it into desmos and find the one point where they touch.

miholovesjdramas
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This problem can be simplified by completing the square.

X^2 + 8x + (a + 1.5) = (x + 4)^2

Equating “c” terms,
a + 1.5 = 16
a = 14.5

If one is interested in the value of x,
x = -4
The value of the vertex.

The completed square is actually in the vertex form with k = 0.

OverclockingCowboy