The problem has two parts. First, we need to find the points of intersection of two given graphs, $y = 2x + 5$ and $y = 2x^2 + x - 1$. Second, we need to find the value of $y$ on the curve $y = 2x^2 + x - 1$ when $x = -2.5$.

AlgebraQuadratic EquationsSystems of EquationsLinear EquationsCurve IntersectionFunctions
2025/4/10

1. Problem Description

The problem has two parts.
First, we need to find the points of intersection of two given graphs, y=2x+5y = 2x + 5 and y=2x2+x1y = 2x^2 + x - 1.
Second, we need to find the value of yy on the curve y=2x2+x1y = 2x^2 + x - 1 when x=2.5x = -2.5.

2. Solution Steps

Part 1:
To find the points of intersection, we need to solve the system of equations:
y=2x+5y = 2x + 5
y=2x2+x1y = 2x^2 + x - 1
Set the expressions for yy equal to each other:
2x+5=2x2+x12x + 5 = 2x^2 + x - 1
Rearrange the equation to form a quadratic equation:
2x2+x12x5=02x^2 + x - 1 - 2x - 5 = 0
2x2x6=02x^2 - x - 6 = 0
We can factor this quadratic equation:
(2x+3)(x2)=0(2x + 3)(x - 2) = 0
So, the solutions for xx are:
2x+3=0x=32=1.52x + 3 = 0 \Rightarrow x = -\frac{3}{2} = -1.5
x2=0x=2x - 2 = 0 \Rightarrow x = 2
Now, we find the corresponding yy values:
For x=1.5x = -1.5, y=2(1.5)+5=3+5=2y = 2(-1.5) + 5 = -3 + 5 = 2
For x=2x = 2, y=2(2)+5=4+5=9y = 2(2) + 5 = 4 + 5 = 9
Therefore, the points of intersection are (1.5,2)(-1.5, 2) and (2,9)(2, 9).
Part 2:
We are given x=2.5x = -2.5 and the curve y=2x2+x1y = 2x^2 + x - 1.
Substitute x=2.5x = -2.5 into the equation:
y=2(2.5)2+(2.5)1y = 2(-2.5)^2 + (-2.5) - 1
y=2(6.25)2.51y = 2(6.25) - 2.5 - 1
y=12.52.51y = 12.5 - 2.5 - 1
y=101y = 10 - 1
y=9y = 9
Thus, the value of yy on the curve when x=2.5x = -2.5 is 99.

3. Final Answer

For Question 48, the points of intersection are (2.0, 9.0) and (-1.5, 2.0).
For Question 49, if x=2.5x = -2.5, the value of y on the curve is

9. The answer for Question 48 is A.

The answer for Question 49 is C.

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