DUIVING Qudulal Equations by Factorin
Question 3
A student solved a quadratic equation as shown here:
2x2 + 5x = 12
x(2x + 5) = 12
x= 12or 2x + 5 = 12
x= 12or 2x + 5 - 5 = 12-5
x= 12or 2x = 7
x= 12or x=?
x=1,12
Explain the errors in the process. Then correct the errors, and solve the equation.
BI V X X Font Sizes - A - AS EIE
N

i think it’s a i believe

any of them that add up to 180 degrees.

x^2 + 81

we can factor this using difference of square binomials.

rewrite the equation:

x^2 - (-81)

factor:

(a^2 - b^2) = (√a^2 + √b^2)(√a^2 - √b^2)

(x^2 - (-81) = (x + √-81)(x - √-81)

we can remove the - from under the radical by multiplying it by i.

(x^2 - (-81) = (x + i√81)(x - i√81)

(x^2 - (-81) = (x + 9i)(x - 9i)

we can check our answer by using foil:

x^2 - 9ix + 9ix - 81i^2

x^2 - 81^2

i^2 = -1

x^2 + 81