Quadratic Equation Solutions and Perfect Square Trinomials
Learn how to solve quadratic equations by finding square roots and how to make perfect square trinomials. Practice problems included.
Quadratic Equation Solutions and Perfect Square Trinomials
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Presentation Transcript
ANSWER The solutions are 4 + 5 = 9 and 4 –5 = – 1. EXAMPLE 1 Solve a quadratic equation by finding square roots Solve x2 – 8x + 16 = 25. x2 – 8x + 16 = 25 Write original equation. (x – 4)2 = 25 Write left side as a binomial squared. x – 4 = +5 Take square roots of each side. x = 4 + 5 Solve for x.
16 = 8 2 EXAMPLE 2 Make a perfect square trinomial Find the value of cthat makes x2 + 16x + ca perfect square trinomial. Then write the expression as the square of a binomial. SOLUTION STEP 1 Find half the coefficient of x. STEP 2 Square the result of Step 1. 82 = 64 STEP 3 Replace cwith the result of Step 2. x2 + 16x + 64
EXAMPLE 2 Make a perfect square trinomial ANSWER The trinomialx2 + 16x + c is a perfect square whenc = 64. Thenx2 + 16x + 64 = (x + 8)(x + 8) = (x + 8)2.
for Examples 1 and 2 GUIDED PRACTICE Solve the equation by finding square roots. 1. x2 + 6x + 9 = 36. ANSWER 3 and –9. 2. x2 – 10x + 25 = 1. ANSWER 4 and 6. 3. x2 – 24x + 144 = 100. ANSWER 2 and 22.
81 9 4 2 for Examples 1 and 2 GUIDED PRACTICE Find the value of c that makes the expression a perfect square trinomial.Then write the expression as the square of a binomial. x2 + 14x + c 4. ANSWER 49 ; (x + 7)2 x2 + 22x + c 5. ANSWER 121 ; (x + 11)2 x2 – 9x + c 6. ANSWER ; (x – )2.