Answer:
1. x = 2 , y = -1 , the value is (-1)
2. x = 0 , y = 2.5 , the value is (-11.25)
3. x = -1 , y = -3 , the value is (14)
4. No value of y
5. No values of x and y
6. x = √2 , y = √2 , the value is (9.17)
Explanation:
* Lets do that
- The expression is -3x² + 2y² + 5xy - 2y + 5x² - 3y²
- There are some like terms so lets simplify the expression
∵ -3x² + 5x² = 2x²
∵ 2y² - 3y² = -y²
∴ The simplest form of the expression is
2x² - y² + 5xy - 2y
- Remember: (-)(-) = (+) , (-)(+) = (-) and (-a)² = a²
- Now we are ready to find the values of the expressions
1.
∵ x = 2 , y = -1
∴ 2(2)² - (-1)² + 5(2)(-1) - 2(-1) = 2(4) - 1 - 10 + 2 = -1
∴ x = 2 , y = -1 , the value is (-1)
2.
∵ x = 0 , y = 2.5
∴ 2(0)² - (2.5)² + 5(0)(2.5) - 2(2.5) = 0 - 6.25 - 0 - 5 = -11.25
∴ x = 0 , y = 2.5 , the value is (-11.25)
3.
∵ x = -1 , y = -3
∴ 2(-1)² - (-3)² + 5(-1)(-3) - 2(-3) = 2(1) - 9 + 15 + 6 = 14
∴ x = -1 , y = -3 , the value is (14)
6.
∵ x = √2 , y = √2
∴ 2(√2)² - (√2)² + 5(√2)(√2) - 2(√2) = 2(2) - 2 + 10 + 2√2 = 9.17
∴ x = √2 , y = √2 , the value is (9.17)