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Solving Two-Step Equations. You will solve equations by undoing operations using properties of equality. Essential Question: How do you solve two-step equations? TP: Construct and solve two step equations for real world problems by combining like terms. Steps for Solving Two-Step Equations
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Solving Two-StepEquations You will solve equations by undoing operations using properties of equality. Essential Question: How do you solve two-step equations? TP: Construct and solve two step equations for real world problems by combining like terms
Steps for Solving Two-Step Equations • Solve for any Addition or Subtraction on the variable side of equation by “undoing” the operation from both sides of the equation. • Solve any Multiplication or Division from variable side of equation by “undoing” the operation from both sides of the equation. Inverse Operations Addition Subtraction Multiplication Division Whatever you do to one side, you must do to the other side to keep property of equality.
Example 1: Solve 4x – 5 = 15 4x – 5 = 15 +5 +5 (Add 5 to both sides) 4x = 20 (Simplify) 4 4 (Divide both sides by 4) x = 5 (Simplify) Check: 4(5) -5 =15 20 – 5 = 15 15 =15
Solve + 5 = 11. 11 + 5 = + 5 – 5 = 11 – 5 x x x x x 6 = 2 2 2 2 2 x = 12 2 = 2 6 ANSWER The solution is 12. Check by substituting 12 for xin the original equation. EXAMPLE 2 Solve a two-step equation Write original equation. Subtraction Property of Equality Simplify. Multiplication Property of Equality. Simplify.
11 ? 12 + 5 = 11 + 5 = 2 11 11 = x 2 EXAMPLE 2 Solve a two-step equation CHECK Write original equation. Substitute 12 for x. Simplify. Solution checks.
5x + 9 = 24 5x + 9 – 9 = 24 – 9 15 5x = = 15 5x 5 5 3 x = for Example 1 &2 GUIDED PRACTICE Solve the equation. Check your solution. 1. 5x + 9 = 24 SOLUTION Write original equation. Subtraction Property of Equality Simplify. Division Property of Equality Simplify.
5x + 9 = 24 ? 53 + 9 = 24 24 = 24 ANSWER The solution is 3. Check by substituting 3 for xin the original equation. for Example 1 GUIDED PRACTICE CHECK Write original equation. Substitute 3 for x. Simplify. Solution check.
4y – 4 = 16 4y – 4 + 4 = 16 + 4 20 4y = 20 4y = 4 4 y = 5 for Example 1 GUIDED PRACTICE Solve the equation. Check your solution. 2. 4y – 4= 16 SOLUTION Write original equation. Addition Property of Equality Simplify. Division Property of Equality. Simplify.
4y – 4 = 16 ? 4(5) – 4 = 16 16 = 16 ANSWER The solution is 5. Check by substituting 5 for yin the original equation. for Example 1 GUIDED PRACTICE CHECK Write original equation. Substitute 5 for y. Simplify. Solution checks.
3. – 1 = –7 – 1 = – 7 z z z z z – 1 + 7 = – 7 + 7 3 3 3 3 3 6 = 3 6 = 3 z 18 = for Example 1 GUIDED PRACTICE Solve the equation. Check your solution. SOLUTION Write original equation. Add 7 to each side. Simplify. Multiply each side by 3. Simplify.
– 1 = – 7 z ? 18 3 – 1 = – 7 3 – 1 = – 1 ANSWER The solution is 18. Check by substituting 18 for zin the original equation. for Example 1 GUIDED PRACTICE CHECK Write original equation. Substitute 18 for z. Simplify. Solution checks.
= 3x 21 3 3 EXAMPLE 3 Solve a two-step equation by combining like terms Solve7x – 4x = 21 7x – 4x = 21 Write original equation. 3x = 21 Combine like terms. Divide each side by 3. x = 7 Simplify.
5t 35 5 = 5 for Examples 3 GUIDED PRACTICE Solve the equation. Check your solution. 5. 8t – 3t = 35 8t – 3t = 35 Write original equation. 5t = 35 Substract the like terms Divide each side by 5 t=7 Simplify.
? 8t– 3t= 35 CHECK 8(7) – 3(7) = 35 ? 56 – 21 = 35 for Examples 3 GUIDED PRACTICE Write original equation. Substitute7 fort. Multiply. 35=35 Simplify. Solution checks.
for Example 4 GUIDED PRACTICE Jobs 10. Kim has a job where she makes $8 per hour plus tips. Yesterday, Kim made $53 dollars, $13 of which was from tips. How many hours did she work? SOLUTION 53 = 13 + 8h Write the equation 53–13= 13 –13 + 8h Subtraction Property of Equality. 40 = 8h Simplify. 5 = h Division Property of Equality
ANSWER She worked for 5 hours for Example 4 GUIDED PRACTICE
How do you solve two-step equations? Essential Question: