Question

6)Quais são as raízes da função f(x) = x²-7x+10
a)-2 e -5
b)2 e 5
c)5 e 5
d)3 e 4

Answer 1

$\Large\boxed{\begin{array}{l}\sf x^2-7x+10=0\\\sf \Delta=b^2-4ac\\\sf\Delta=(-7)^2-4\cdot 1\cdot10\\\sf\Delta=49-40\\\sf\Delta=9\\\sf x=\dfrac{-b\pm\sqrt{\Delta}}{2a}\\\\\sf x=\dfrac{-(-7)\pm\sqrt{9}}{2\cdot1}\\\\\sf x=\dfrac{7\pm3}{2}\begin{cases}\sf x_1=\dfrac{7+3}{2}=\dfrac{10}{2}=5\\\\\sf x_2=\dfrac{7-3}{2}=\dfrac{4}{2}=2\end{cases}\\\\\huge\boxed{\boxed{\boxed{\boxed{\sf\red{\maltese}\blue{~alternativa~b}}}}}\end{array}}$