Expression Simplification E2833C
1. Simplify the expression $4x^2 + 3x - 5 - (-3x^2 - 8x + 2)$.
Start by distributing the minus sign to the second polynomial:
$$4x^2 + 3x - 5 + 3x^2 + 8x - 2$$
Combine like terms:
$$4x^2 + 3x^2 = 7x^2$$
$$3x + 8x = 11x$$
$$-5 - 2 = -7$$
So, the simplified form is:
$$7x^2 + 11x - 7$$
2. Simplify the expression $(5x^2 - 9xy - 11y^2) - (7x^2 - 2xy + 2y^2)$.
Distribute the minus sign:
$$5x^2 - 9xy - 11y^2 - 7x^2 + 2xy - 2y^2$$
Combine like terms:
$$5x^2 - 7x^2 = -2x^2$$
$$-9xy + 2xy = -7xy$$
$$-11y^2 - 2y^2 = -13y^2$$
Simplified expression:
$$-2x^2 - 7xy - 13y^2$$
3. Calculate the cost $C$ when $C = RT^2 - 3T + 8$, with $R=4$ and $T=-3$.
Substitute values:
$$C = 4(-3)^2 - 3(-3) + 8$$
Calculate powers and products:
$$4 \times 9 + 9 + 8 = 36 + 9 + 8$$
Sum all terms:
$$36 + 9 + 8 = 53$$
So, the cost is 53 dollars.
4. Daniel is $x$ years old. His brother is $x + 5$ years old.
The product of their ages is given by:
$$x(x + 5) = 71$$
Expand:
$$x^2 + 5x = 71$$
Rewrite as a quadratic equation:
$$x^2 + 5x - 71 = 0$$
Use the quadratic formula:
$$x = \frac{-5 \pm \sqrt{5^2 - 4 \times 1 \times (-71)}}{2 \times 1} = \frac{-5 \pm \sqrt{25 + 284}}{2} = \frac{-5 \pm \sqrt{309}}{2}$$
Calculate approximate roots:
$$\sqrt{309} \approx 17.58$$
Possible solutions:
$$x = \frac{-5 + 17.58}{2} = 6.29$$
$$x = \frac{-5 - 17.58}{2} = -11.29$$
Since age cannot be negative, Daniel is approximately 6 years old.
His brother's age:
$$6 + 5 = 11$$
Final answers:
1) $7x^2 + 11x - 7$
2) $-2x^2 - 7xy - 13y^2$
3) 53
4) Daniel is 6 years old, his brother is 11 years old.