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Question
Complete the following activity to solve the given quadratic equation by formula method.
2x2 + 13x + 15 = 0
Activity: 2x2 + 13x + 15 = 0
a = (______), b = 13, c = 15
b2 – 4ac = (13)2 – 4 × 2 × (______)
= 169 – 120
b2 – 4ac = 49
x = `(-"b" +- sqrt("b"^2 - 4"ac"))/(2"a")`
x = `(- ("______") +- sqrt(49))/4`
x = `(-13 +- ("______"))/4`
x = `(-6)/4` or x = `(-20)/4`
x = (______) or x = (______)
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Solution
2x2 + 13x + 15 = 0
a = 2, b = 13, c = 15
b2 – 4ac = (13)2 – 4 × 2 × 15
= 169 – 120
b2 – 4ac = 49
x = `(-"b" +- sqrt("b"^2 - 4"ac"))/(2"a")`
x = `(- (bb(13)) +- sqrt(49))/4`
x = `(-13 +- bb(7))/4`
x = `(-13 + 7)/4` or x = `(-13 - 7)/4`
x = `(-6)/4` or x = `(-20)/4`
x = `bb((-3)/2)` or x = − 5
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