Expand and simplify: \( \begin{array}{lll}\text { (1) } 2 x(3 x-4 y)-\left(7 x^{2}-2 x y\right) & \text { (2) } \quad(5 y+1)^{2}-(3 y+4)(2-3 y) \\ \text { (3) }(2 x+y)^{2}-(3 x-2 y)^{2}+(x-4 y)(x+4 y) \\ \text { (4) } x^{6}+\left(x^{3}-3 y\right)\left(x^{3}+3 y\right) & \text { (5) } \quad(3 a+b)(3 a-b)(2 a+5 b)\end{array} \)
Real Tutor Solution
Answer
Solution
Reviewed and approved by the UpStudy tutoring team
Mind Expander
Let's tackle each expression one by one! 1. \( 2x(3x-4y) - (7x^2 - 2xy) \): First, distribute \(2x\) to get \(6x^2 - 8xy\). Now, simplify: \[ 6x^2 - 8xy - 7x^2 + 2xy = (6x^2 - 7x^2) + (-8xy + 2xy) = -x^2 - 6xy. \] 2. \( (5y+1)^2 - (3y+4)(2-3y) \): Start with the first part: \((5y+1)^2 = 25y^2 + 10y + 1\) and expand the second part: \((3y+4)(2-3y) = 6y - 9y^2 + 8 - 12y = -9y^2 - 6y + 8\). Putting these together gives: \[ (25y^2 + 10y + 1) - (-9y^2 - 6y + 8) = 25y^2 + 10y + 1 + 9y^2 + 6y - 8. \] Combine like terms: \(34y^2 + 16y - 7\). 3. \( (2x+y)^2 - (3x-2y)^2 + (x-4y)(x+4y) \): Start by expanding the squares: \((2x+y)^2 = 4x^2 + 4xy + y^2\) and \((3x-2y)^2 = 9x^2 - 12xy + 4y^2\). The difference yields: \[ (4x^2 + 4xy + y^2) - (9x^2 - 12xy + 4y^2) = -5x^2 + 16xy - 3y^2. \] Now for \((x-4y)(x+4y) = x^2 - 16y^2\). Combine: \(-5x^2 + 16xy - 3y^2 + x^2 - 16y^2 = -4x^2 + 16xy - 19y^2\). 4. \( x^6 + (x^3 - 3y)(x^3 + 3y) \): The second part is a difference of squares: \((x^3)^2 - (3y)^2 = x^6 - 9y^2\). Combine with the \(x^6\) term: \[ x^6 + x^6 - 9y^2 = 2x^6 - 9y^2. \] 5. \( (3a+b)(3a-b)(2a+5b) \): Recognizing the format, use the difference of squares: \((3a)^2 - b^2 = 9a^2 - b^2\). Now multiply with \((2a + 5b)\): \[ (9a^2 - b^2)(2a + 5b) = 18a^3 + 45a^2b - 2ab^2 - 5b^3. \] And there you have the expanded and simplified versions!