Math Problem Statement

Solve the system by substitution: y = -2x - 5 and -3x^2 + 4x - y = 8.

Solution

Let's solve the system of equations using substitution. The system is:

y = -2x - 5 \tag{1} -3x^2 + 4x - y = 8 \tag{2}

Step 1: Substitute yy from equation (1) into equation (2).

Substitute y=2x5y = -2x - 5 into equation (2):

3x2+4x(2x5)=8-3x^2 + 4x - (-2x - 5) = 8

Simplify:

3x2+4x+2x+5=8-3x^2 + 4x + 2x + 5 = 8 3x2+6x+5=8-3x^2 + 6x + 5 = 8

Step 2: Solve for xx.

Subtract 8 from both sides:

3x2+6x+58=0-3x^2 + 6x + 5 - 8 = 0 3x2+6x3=0-3x^2 + 6x - 3 = 0

Divide the entire equation by -3 to simplify:

x22x+1=0x^2 - 2x + 1 = 0

This simplifies to:

(x1)2=0(x - 1)^2 = 0

So, x=1x = 1.

Step 3: Substitute x=1x = 1 into equation (1) to find yy.

Using y=2x5y = -2x - 5:

y=2(1)5=25=7y = -2(1) - 5 = -2 - 5 = -7

Thus, the solution is (x,y)=(1,7)(x, y) = (1, -7).

Final Answer:

The solution is (1,7)\boxed{(1, -7)}.

Would you like further details on any part of the solution?

Here are 5 related questions you might find helpful:

  1. How do you solve quadratic equations using factoring?
  2. What are other methods to solve a system of equations, like elimination?
  3. How do you check if a solution is correct for a system of equations?
  4. What are some real-world applications of solving systems of equations?
  5. How do you solve a quadratic equation when it doesn't factor easily?

Tip: Always double-check your solution by plugging the values back into the original equations!

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Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Equations
Substitution Method
Quadratic Equations

Formulas

y = -2x - 5
Quadratic Equation: ax^2 + bx + c = 0
Substitution Method

Theorems

Quadratic Formula

Suitable Grade Level

Grades 9-11