Calculate the value of (-12) + (+7) - (-4).
- 9
- -1 Correct answer.
- -15
- -9
Explanation
Subtracting a negative number becomes addition, so -(-4) = +4. The expression is -12 + 7 + 4. Computing left to right: -12 + 7 = -5, then -5 + 4 = -1.
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Subtracting a negative number becomes addition, so -(-4) = +4. The expression is -12 + 7 + 4. Computing left to right: -12 + 7 = -5, then -5 + 4 = -1.
Follow the order of operations: exponents and multiplication/division before addition/subtraction. (-4)² = 16, (-3) × 2 = -6, and 8 ÷ (-2) = -4, so the expression is 16 + (-6) - (-4) = 16 - 6 + 4 = 14.
Use the common denominator 24: 5/8 = 15/24, 1/6 = 4/24, and 3/4 = 18/24. Then 15/24 - 4/24 + 18/24 = 29/24, which is already in simplest form.
Substitute the values: 4(-3) - 2(-5) = -12 + 10 = -2. The product -2 times -5 is +10, which is then added to -12.
Dividing by a fraction means multiplying by its reciprocal: (3/4) ÷ (-5/8) = (3/4) × (-8/5). Multiplying gives -24/20, which simplifies to -6/5.
Simplify each radical: √72 = 6√2, √50 = 5√2, and √18 = 3√2. Then 6√2 - 5√2 + 3√2 = (6 - 5 + 3)√2 = 4√2.
The first square needs 4 matchsticks, and every square after it adds only 3, because one side is shared with the previous square. For n squares the count is 4 + 3(n − 1) = 3n + 1. Substituting n = 20 gives 3(20) + 1 = 61 matchsticks.
First expand (2x + 3)(3x - 2) = 6x² - 4x + 9x - 6 = 6x² + 5x - 6. Then (x - 1)² = x² - 2x + 1. Subtracting: 6x² + 5x - 6 - (x² - 2x + 1) = 6x² + 5x - 6 - x² + 2x - 1 = 5x² + 7x - 7.
Use FOIL: First 2x·3x = 6x², Outer 2x·5 = 10x, Inner (-1)·3x = -3x, Last (-1)·5 = -5. Combining the middle terms: 10x - 3x = 7x, so the result is 6x² + 7x - 5.
Find two numbers whose product is 3·8 = 24 and sum is 10: those are 6 and 4. Split the middle term: 3x² + 6x + 4x + 8 = 3x(x + 2) + 4(x + 2) = (3x + 4)(x + 2).
Find two numbers whose product is 6·(-3) = -18 and sum is -7: those are -9 and 2. Split the middle term: 6x² - 9x + 2x - 3 = 3x(2x - 3) + 1(2x - 3) = (3x + 1)(2x - 3).
This is a difference of squares: x² - 16 = x² - 4² = (x + 4)(x - 4). The sum and difference of the same two terms produces the difference of squares.
Distribute each term: 6a - 4b - 3a + 3b + 4a + 8b. Collecting a-terms: 6a - 3a + 4a = 7a. Collecting b-terms: -4b + 3b + 8b = 7b. So the result is 7a + 7b.
Multiply the coefficients: 3.2 × 2 = 6.4. Add the exponents: 10⁴ × 10³ = 10⁷. So the product is 6.4 × 10⁷.
The absolute value equation |x - 2| = 5 gives two cases: x - 2 = 5, so x = 7; or x - 2 = -5, so x = -3. Both values satisfy the original equation.
Simplify each radical: √50 = 5√2, √8 = 2√2, and √32 = 4√2. Then 5√2 + 2√2 - 4√2 = (5 + 2 - 4)√2 = 3√2.
First factor: 180 = 2² × 3² × 5. The number of divisors is (2+1)(2+1)(1+1) = 3 × 3 × 2 = 18, by adding one to each exponent and multiplying.
First square: (3x²y)² = 9x⁴y². Then multiply by -2xy³: 9 × (-2) = -18, x⁴ × x = x⁵, y² × y³ = y⁵. The result is -18x⁵y⁵.
Evaluate each power: (-2)³ = -8, (-3)² = 9, and (-6)² = 36. Then -8 × 9 ÷ 36 = -72 ÷ 36 = -2.
Divide both terms by their greatest common divisor, 12: 24 ÷ 12 = 2 and 36 ÷ 12 = 3, so the simplest form is 2 : 3.
Distribute the -2: -2(x² - 3x + 1) = -2x² + 6x - 2. Then (3x² - 2x + 5) + (-2x² + 6x - 2) = (3 - 2)x² + (-2 + 6)x + (5 - 2) = x² + 4x + 3.
Compute each piece: a² = (√3 - 1)² = 3 - 2√3 + 1 = 4 - 2√3, b² = (√3 + 1)² = 3 + 2√3 + 1 = 4 + 2√3, and ab = (√3 - 1)(√3 + 1) = 3 - 1 = 2. Adding: a² + b² = (4 - 2√3) + (4 + 2√3) = 8, so a² + b² - ab = 8 - 2 = 6.
Distribute: 3x - 6 - 2x - 2 = 5, which simplifies to x - 8 = 5. Adding 8 to both sides gives x = 13.
Multiply through by the common denominator 12: 4x + 3x = 84, so 7x = 84, giving x = 12.
From the first equation, y = 2x - 5. Substitute into the second: 3x + 2(2x - 5) = 4, so 3x + 4x - 10 = 4, giving 7x = 14 and x = 2. Then y = 2(2) - 5 = -1.
Double the first equation: 4x + 2y = 14. Subtract the second: (4x + 2y) - (x + 2y) = 14 - 11, so 3x = 3 and x = 1. Substituting back: 2(1) + y = 7, giving y = 5.
Factor: x² + 2x - 8 = (x + 4)(x - 2) = 0, so x = -4 or x = 2. The two numbers 4 and -2 have product -8 and sum 2.
Factor: x² + 3x - 10 = (x + 5)(x - 2) = 0, so x = -5 or x = 2. The two numbers 5 and -2 have product -10 and sum 3.
Using x = (4 ± √(16 + 4))/2 = (4 ± √20)/2 = (4 ± 2√5)/2 = 2 ± √5. Both roots are real and irrational.
Subtract 2x from both sides: x - 7 < 1. Add 7: x < 8. The direction of the inequality is preserved because no multiplication or division by a negative occurred.
Subtract 5: -2x ≥ 6. Divide by -2, flipping the inequality: x ≤ -3. Dividing or multiplying by a negative reverses the inequality.
From 2x - 1 > 3: 2x > 4, so x > 2. From x + 2 ≤ 9: x ≤ 7. Combining: x must be greater than 2 and at most 7, i.e., 2 < x ≤ 7.
Let a be the number of adult tickets. Then a + (80 - a) = 80, and the revenue is 200a + 100(80 - a) = 11,200. Simplifying: 100a + 8,000 = 11,200, so 100a = 3,200 and a = 32.
Let the son's current age be s. Then the father is 3s now. In 10 years: 3s + 10 = 2(s + 10). Solving: 3s + 10 = 2s + 20, so s = 10.
Downstream speed = 30/2 = 15 km/h = (boat + current). Upstream speed = 30/3 = 10 km/h = (boat - current). Subtracting: (boat + current) - (boat - current) = 2 × current = 5, so current = 2.5 km/h.
Let n be the number of notebooks. Then n + p = 10 and 120n + 80p = 920. Substituting p = 10 - n: 120n + 80(10 - n) = 920, so 40n + 800 = 920, giving 40n = 120 and n = 3.
Multiply by 6x(x + 1): 6(x + 1) + 6x = 5x(x + 1), so 12x + 6 = 5x² + 5x. Rearranging: 5x² - 7x - 6 = 0. Factoring: (5x + 3)(x - 2) = 0, so x = 2 or x = -3/5. The positive integer solution is x = 2.
Cross-multiply: 3 × 20 = 4 × x, so 60 = 4x, giving x = 15.
The absolute value equation gives two cases: 2x + 1 = 7, so 2x = 6 and x = 3; or 2x + 1 = -7, so 2x = -8 and x = -4.
Let the width be w; then the length is w + 4. The area is w(w + 4) = 96, so w² + 4w - 96 = 0. Factoring: (w + 12)(w - 8) = 0, giving w = 8 (the positive root, since width must be positive).
The tile counts go up by 3 each time and start at 5, so the n-th figure uses 5 + 3(n − 1) = 3n + 2 tiles. Setting 3n + 2 = 92 gives 3n = 90, so n = 30. Checking: 3(30) + 2 = 92.
Let n be the number. The inequality is 2n + 5 ≤ 17. Subtracting 5: 2n ≤ 12. Dividing by 2: n ≤ 6. The largest integer satisfying this is n = 6.
Substitute x = -4: y = 3(-4) = -12. In a proportional relationship, a negative input produces a negative output.
First find k: k = xy = 2 × 6 = 12. So y = 12/x. When x = -4: y = 12/(-4) = -3. A negative x gives a negative y in an inverse proportion with positive k.
Substitute x = 4: y = 2(4) - 3 = 8 - 3 = 5. The slope 2 multiplies x first, then the intercept -3 is subtracted.
The slope is (y₂ - y₁)/(x₂ - x₁) = (15 - 3)/(4 - (-2)) = 12/6 = 2. The denominator uses the difference including the sign of -2.
Using point-slope form: y - 5 = 2(x - 2), so y = 2x - 4 + 5 = 2x + 1. The intercept is b = 5 - 2(2) = 1.
Set the expressions equal: x + 2 = -x + 6, so 2x = 4 and x = 2. Substituting back: y = 2 + 2 = 4. The intersection is (2, 4).
Substitute (3, 18): 18 = a(3²) = 9a, so a = 2 and the function is y = 2x². When x = -2: y = 2(-2)² = 2(4) = 8. Squaring removes the sign, so y is positive.
Because a = 2 is positive, the graph is a parabola opening upward with its lowest point at the origin. The value x = 0 lies inside the interval -1 ≤ x ≤ 3, so the smallest value of y is 2(0)² = 0. The largest value comes from whichever endpoint is furthest from 0, namely x = 3, giving y = 2(3)² = 18. The range is therefore 0 ≤ y ≤ 18.