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30. 5 x. =. 5. 5. EXAMPLE 1. Solve an equation by combining like terms. Solve 8 x – 3 x – 10 = 20. 8 x – 3 x – 10 = 20. Write original equation. 5 x – 10 = 20. Combine like terms. 5 x – 10 + 10 = 20 + 10. Add 10 to each side. 5 x = 30. Simplify.
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30 5x = 5 5 EXAMPLE 1 Solve an equation by combining like terms Solve 8x – 3x – 10 = 20. 8x – 3x – 10 = 20 Write original equation. 5x – 10 = 20 Combine like terms. 5x – 10 + 10= 20 + 10 Add 10 to each side. 5x = 30 Simplify. Divide each side by 5. x = 6 Simplify.
SOLUTION When solving an equation, you may feel comfortable doing some steps mentally. Method 2 shows a solution where some steps are done mentally. EXAMPLE 2 Solve an equation using the distributive property Solve 7x +2(x + 6) = 39.
METHOD2 Do Some Steps Mentally = 9x 27 9 9 EXAMPLE 2 METHOD1 Show All Steps 7x + 2(x + 6) = 39 7x + 2(x + 6) = 39 7x + 2x + 12 = 39 7x + 2x + 12 = 39 9x + 12 = 39 9x + 12 = 39 9x + 12 – 12= 39 – 12 9x = 27 9x = 27 x = 3 x =3
SOLUTION ANSWER In Step 2, the distributive property is used to simplify the left side of the equation. Because –4(x– 3) = –4x + 12, Step 2 should be 5x – 4x + 12 = 17. The correct answer is D. A B C D EXAMPLE 3 Standardized Test Practice
1. 9d – 2d + 4 = 32 ANSWER 4 for Examples 1, 2, and 3 GUIDED PRACTICE Solve the equation. Check your solution.
2. 2w + 3(w + 4) = 27 ANSWER 3 EXAMPLE 2 for Examples 1, 2, and 3 GUIDED PRACTICE Solve the equation. Check your solution.
6x – 2(x – 5) = 46 3. ANSWER 9 EXAMPLE 2 for Examples 1, 2, and 3 GUIDED PRACTICE Solve the equation. Check your solution.