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Rewrite linear expressions

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5513068
Rewrite \(5(x + 2)\) in an equivalent form without parentheses.

Hints

- Which property lets you remove parentheses when a factor is outside them? - The outside factor applies to each term inside the parentheses. - After removing the parentheses, check that each original term has been accounted for.

Solution

Distribute \(5\) to both terms inside the parentheses: \(5(x + 2) = 5x + 10\).

Answer

\(5x + 10\)
5129108
Rewrite \(f(x)=(2x+1)(x-3)-2x^2+4x\) as a linear expression in the form \(mx+b\).

Hints

- Expand the product before combining any terms. - Group the quadratic terms, linear terms, and constants separately. - Check whether the quadratic terms cancel completely.

Solution

1. Expand the product: \((2x+1)(x-3)=2x^2-5x-3\). 2. Substitute this into the expression: \(f(x)=2x^2-5x-3-2x^2+4x\). 3. Combine like terms. The quadratic terms cancel, and \(-5x+4x=-x\), so \(f(x)=-x-3\).

Answer

\(f(x)=-x-3\)
5129118
Rewrite \(f(x)=(x-4)^2-x(x-10)-15\) as a simplified linear expression. Explain how the simplified form shows that \(f\) is linear.

Hints

- Expand both products carefully before combining terms. - Keep track of the subtraction in front of \(x(x-10)\). - After simplifying, compare the result with the general linear form \(mx+b\).

Solution

1. Expand the square and product: \((x-4)^2=x^2-8x+16\) and \(x(x-10)=x^2-10x\). 2. Substitute and combine like terms: \(f(x)=x^2-8x+16-x^2+10x-15=2x+1\). 3. The quadratic terms cancel, leaving the form \(mx+b\). Therefore, \(f\) is linear.

Answer

\(f(x)=2x+1\). It is linear because the simplified expression has the form \(mx+b\).
5129518
Rewrite each expression in the form \(y=mx+b\): \(f(x)=2(x-3)+4\) and \(g(x)=5-\frac{1}{2}x-2\).

Hints

- Remove the parentheses in \(f\) using the distributive property. - Combine constant terms separately from variable terms. - Arrange each result with the \(x\)-term first and the constant second.

Solution

1. Distribute and combine constants in \(f\): \(f(x)=2x-6+4=2x-2\). 2. Combine the constants in \(g\): \(g(x)=-\frac{1}{2}x+5-2=-\frac{1}{2}x+3\).

Answer

\(f(x)=2x-2\) \(g(x)=-\frac{1}{2}x+3\)
5519898
The diagram shows a rectangle. Write an equivalent expression without parentheses for its area.
Figure for problem 551989

Hints

- Write the rectangle's area as length times width. - Use the distributive property to remove the parentheses.

Solution

1. The area is \(4(x + 3)\). 2. Distribute \(4\) to both terms inside the parentheses: \(4x + 12\).

Answer

\(4x + 12\) square units
5519908
A student rewrites \(5(2x - 3)\) as \(10x - 3\). Is the rewrite correct? If not, give the correct equivalent expression and explain the error.

Hints

- Check whether the outside factor was applied to every term inside the parentheses. - Compare the original and rewritten expressions term by term.

Solution

1. The rewrite is not correct because the factor \(5\) must multiply both terms inside the parentheses. 2. Distributing gives \(5(2x) - 5(3) = 10x - 15\).

Answer

No. The correct equivalent expression is \(10x - 15\). The student multiplied only the first term by \(5\).
5519918
Rewrite \(3(2x + 5) - 4x + 7\) as a single simplified linear expression.

Hints

- Remove the parentheses before combining terms. - Combine variable terms with variable terms and constants with constants.

Solution

1. Distribute \(3\): \(6x + 15 - 4x + 7\). 2. Combine like terms: \(6x - 4x = 2x\) and \(15 + 7 = 22\). 3. The simplified expression is \(2x + 22\).

Answer

\(2x + 22\)
5129128
Consider \(f(x)=\frac{1}{2}x(4-2x)+x^2+3\) and \(g(x)=2(x+1.5)\). Rewrite both expressions in simplified linear form and determine whether they are equivalent for every value of \(x\).

Hints

- Simplify each expression separately. - In \(f\), check what happens to the two \(x^2\)-terms. - Equivalent expressions have the same simplified form for every value of the variable.

Solution

1. Distribute in \(f\): \(\frac{1}{2}x(4-2x)=2x-x^2\), so \(f(x)=2x-x^2+x^2+3=2x+3\). 2. Distribute in \(g\): \(g(x)=2x+3\). 3. Both expressions simplify to \(2x+3\), so they are equivalent for every value of \(x\).

Answer

\(f(x)=2x+3\) and \(g(x)=2x+3\). Yes, they are equivalent for every value of \(x\).
5519928
Find the value of \(k\) that makes \(k(x + 4) + 2x\) equivalent to \(7x + 20\) for every value of \(x\). Explain how you know.

Hints

- First rewrite the expression with \(k\) by distributing and combining like terms. - For two linear expressions to be equivalent for every \(x\), compare both the variable coefficient and the constant term. - Check that the same value of \(k\) satisfies both comparisons.

Solution

1. Rewrite the left side as \((k + 2)x + 4k\). 2. Equivalent linear expressions must have matching coefficients of \(x\) and matching constant terms. 3. Matching the coefficient gives \(k + 2 = 7\), so \(k = 5\). Matching the constant gives \(4k = 20\), which also gives \(k = 5\). 4. Both conditions agree, so \(k = 5\).

Answer

\(k = 5\)
5519938
A rectangle has length \(2x + 1\) units and width \(x - 2\) units, where \(x > 2\). Write its perimeter as a single simplified linear expression.

Hints

- A rectangle has two lengths and two widths. - Write the perimeter expression before simplifying it. - Distribute first, then combine like terms.

Solution

1. Use the perimeter formula: \(P = 2(2x + 1) + 2(x - 2)\). 2. Distribute: \(P = 4x + 2 + 2x - 4\). 3. Combine like terms: \(P = 6x - 2\).

Answer

\(6x - 2\) units

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