Evaluate (−3) + 5 − (−2).
- 4 Correct answer.
- −6
- 0
- 6
Explanation
Work left to right: (−3) + 5 = 2, then 2 − (−2) = 2 + 2 = 4. Subtracting a negative number is the same as adding its opposite, so the result is 4.
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Work left to right: (−3) + 5 = 2, then 2 − (−2) = 2 + 2 = 4. Subtracting a negative number is the same as adding its opposite, so the result is 4.
First (−4) × 3 = −12. Then −12 ÷ (−2) = 6. A negative divided by a negative is positive, so the answer is 6.
Distribute first: −2(x + 4) = −2x − 8. Then 3x − 2x − 8 − 7 = x − 15. Combining like terms gives x − 15.
Substitute: x² = (−2)² = 4, 2xy = 2(−2)(3) = −12, y² = 9. So 4 − (−12) + 9 = 4 + 12 + 9 = 25. Equivalently, x² − 2xy + y² = (x − y)² = (−5)² = 25.
Use FOIL: x·x = x², x·(−5) = −5x, 3·x = 3x, 3·(−5) = −15. Combine the middle terms: −5x + 3x = −2x. So the result is x² − 2x − 15.
We need two numbers that multiply to +12 and add to −7. Both must be negative: −3 and −4 give (−3)(−4) = 12 and −3 + (−4) = −7. So x² − 7x + 12 = (x − 3)(x − 4).
We seek a factorization (2x + a)(x + b) with a·b = −3 and 2b + a = −5. Try a = 1, b = −3: a·b = −3 and 2(−3) + 1 = −5. Both conditions hold, so 2x² − 5x − 3 = (2x + 1)(x − 3).
Simplify each radical: √72 = √(36·2) = 6√2, and √32 = √(16·2) = 4√2. Then 6√2 − 4√2 = 2√2. Like radicals combine by adding or subtracting their coefficients.
This is a difference of squares: (a + b)(a − b) = a² − b² with a = 2, b = √3. So 2² − (√3)² = 4 − 3 = 1. The radicals cancel, leaving the rational number 1.
Multiply numerator and denominator by √3: 6√3 / (√3·√3) = 6√3 / 3 = 2√3. The denominator becomes the rational number 3, and 6/3 = 2.
Compute each term: a²b = (2)²(−3) = 4(−3) = −12, and ab² = (2)(−3)² = 2(9) = 18. Adding: −12 + 18 = 6. Alternatively, factor as ab(a + b) = (2)(−3)(2 + (−3)) = (−6)(−1) = 6.
Simplify each radical: √8 = √(4·2) = 2√2, and √18 = √(9·2) = 3√2. Then 3√2 + 2√2 − 3√2 = 2√2. The first and last terms cancel, leaving 2√2.
Use the identity (a − b)² = a² − 2ab + b² with a = x, b = 2: x² − 2(x)(2) + 2² = x² − 4x + 4. The middle term is negative and the constant is positive.
Compute each power: (−2)³ = −8, and (−1)² = 1. Then −8 × 1 = −8. The cube of a negative is negative, and the square of a negative is positive.
Distribute: 2x + 6 − 3x + 3 + x. Combine like terms: (2x − 3x + x) + (6 + 3) = 0x + 9 = 9. The x-terms cancel completely, leaving the constant 9.
From √x = 5, square both sides: x = 25. Then x − 6 = 25 − 6 = 19. The square root undoes the squaring for non-negative x.
This is a difference of squares: a² − b² = (a − b)(a + b) with a = 2x, b = 3. So 4x² − 9 = (2x)² − 3² = (2x − 3)(2x + 3). The two factors are conjugates.
First multiply (x + 1)(x + 2) = x² + 3x + 2. Then multiply by (x + 3): (x² + 3x + 2)(x + 3) = x³ + 3x² + 3x² + 9x + 2x + 6 = x³ + 6x² + 11x + 6. The coefficient of x² is 6.
Subtract 2x from both sides: x − 7 = 5. Add 7: x = 12. Check: 3(12) − 7 = 29 and 2(12) + 5 = 29, confirming the solution.
Distribute: 2x − 6 = 4 − x. Add x: 3x − 6 = 4. Add 6: 3x = 10. Divide by 3: x = 10/3. Checking: 2(10/3 − 3) = 2(1/3) = 2/3 and 4 − 10/3 = 2/3.
Add the two equations: (x + y) + (x − y) = 7 + 1, so 2x = 8, x = 4. Substitute into x + y = 7: 4 + y = 7, y = 3. The solution is x = 4, y = 3.
From x − y = 1, x = y + 1. Substitute into 2(y + 1) + 3y = 12: 2y + 2 + 3y = 12, so 5y = 10, y = 2. Then x = 2 + 1 = 3. The solution is x = 3, y = 2.
From 2x + y = 9, y = 9 − 2x. Substitute: 3x + 2(9 − 2x) = 16, so 3x + 18 − 4x = 16, −x = −2, x = 2. Then y = 9 − 2(2) = 5. The solution is x = 2, y = 5.
Factor: x² − 5x + 6 = (x − 2)(x − 3) = 0. By the zero-product property, x − 2 = 0 or x − 3 = 0, so x = 2 or x = 3. Both are positive since the sum is +5 and the product is +6.
Factor: we need two numbers multiplying to −7 and adding to −6. Those are −7 and +1: (x − 7)(x + 1) = 0, so x = 7 or x = −1. The product is negative, so the roots have opposite signs.
Here a = 1, b = −4, c = −1. The discriminant is b² − 4ac = 16 + 4 = 20, so √(discriminant) = √20 = 2√5. Then x = (4 ± 2√5)/2 = 2 ± √5. The two roots are 2 + √5 and 2 − √5.
Add 5 to both sides: 2x < 12. Divide by 2 (positive, so the inequality direction is unchanged): x < 6. The inequality is strict (<), so 6 is not included.
Subtract 1: −3x ≤ 9. Divide by −3 and flip the inequality (dividing by a negative reverses the sign): x ≥ −3. The flip is the key step many students miss.
Let the number be n. The equation is n + 5 = 3n − 7. Subtract n: 5 = 2n − 7. Add 7: 12 = 2n. Divide by 2: n = 6. Check: 6 + 5 = 11 and 3(6) − 7 = 11.
Let the numbers be a and b with a > b. Then a + b = 20 and a − b = 4. Add the equations: 2a = 24, so a = 12. The larger number is 12 (and the smaller is 8).
Let p = pencils, e = erasers. Then p + e = 10 and 80p + 120e = 920. From the first equation p = 10 − e. Substitute: 80(10 − e) + 120e = 920, so 800 − 80e + 120e = 920, 40e = 120, e = 3. The student bought 3 erasers (and 7 pencils).
Let the width be w. Then the length is w + 3. The perimeter is 2(w + w + 3) = 26, so 2(2w + 3) = 26, 4w + 6 = 26, 4w = 20, w = 5. The width is 5 cm (and the length is 8 cm).
We need two numbers multiplying to −8 and adding to +2. Those are +4 and −2: (x + 4)(x − 2) = 0, so x = −4 or x = 2. The product is negative, so the roots have opposite signs.
Let the son's current age be s. Then the father is 4s now. In 6 years: 4s + 6 = 3(s + 6). Expand: 4s + 6 = 3s + 18. Subtract 3s: s + 6 = 18. Subtract 6: s = 12. Verify: father now 48, in 6 years 54; son now 12, in 6 years 18; 54 = 3(18) = 54. So the son is 12 now.
From 2x − 1 < 5: 2x < 6, x < 3. From x + 3 ≥ 2: x ≥ −1. Combining: −1 ≤ x < 3. The integers satisfying both are −1, 0, 1, 2. Note that 3 is excluded because the first inequality is strict.
Direct proportion means y = kx. Find k: 15 = k(5), so k = 3. Then when x = 8: y = 3(8) = 24. The ratio y/x = 3 is constant for all valid x.
Inverse proportion means y = k/x. Find k: 6 = k/4, so k = 24. Then when x = 8: y = 24/8 = 3. As x doubles from 4 to 8, y halves from 6 to 3.
Slope = (y₂ − y₁)/(x₂ − x₁) = (7 − 3)/(2 − 1) = 4/1 = 4. The slope is the rate of change of y with respect to x, which is 4 here.
Substitute the point into y = −2x + b: 4 = −2(3) + b, so 4 = −6 + b, and b = 10. The y-intercept is 10, so the function is y = −2x + 10.
On the x-axis, y = 0. Set 0 = 3x − 5, so 3x = 5, x = 5/3. The x-intercept is (5/3, 0). The y-intercept (0, −5) is a different point.
Set the equations equal: 2x + 1 = −x + 4. Add x: 3x + 1 = 4. Subtract 1: 3x = 3, x = 1. Then y = 2(1) + 1 = 3. The intersection is (1, 3). Verify: −1 + 4 = 3. ✓
The vertex x-coordinate is x = −b/(2a) = −(−4)/(2·1) = 2. Substitute: y = (2)² − 4(2) + 3 = 4 − 8 + 3 = −1. The vertex is (2, −1), the minimum point of the parabola.
The axis of symmetry is the vertical line x = −b/(2a) = −(−4)/(2·1) = 2. This is the x-coordinate of the vertex, and the parabola is symmetric about this line.
Substitute x = 3: y = −2(3)² = −2(9) = −18. The negative coefficient means the parabola opens downward, and the square ensures y is always non-positive.
Set y = 0: x² − 6x + 5 = 0. Factor: (x − 1)(x − 5) = 0, so x = 1 or x = 5. The x-intercepts are (1, 0) and (5, 0). Both roots are positive since their sum is +6 and product is +5.
Substitute t = 2.5: d = 60(2.5) = 150. The car travels 150 km in 2.5 hours at 60 km/h. This is a direct proportion with constant of proportionality 60.
Shifting a graph up by 2 units means adding 2 to the y-value: y = (3x − 6) + 2 = 3x − 4. The slope stays the same; only the y-intercept changes from −6 to −4.
At x = 1, y = 1. At x = 3, y = 9. The average rate of change is (9 − 1)/(3 − 1) = 8/2 = 4. This is the slope of the secant line connecting (1, 1) and (3, 9).
Substitute the point: 5 = k/2, so k = 10. The constant of inverse proportionality is the product x·y, which is 2 × 5 = 10 for every point on the curve.
The maximum occurs at the vertex of the parabola h = −5t² + 20t. The t-coordinate is t = −b/(2a) = −20/(2·(−5)) = −20/(−10) = 2. The ball reaches maximum height at t = 2 seconds.