Question

What are the solutions to the equation x2 + 6 = 87?

  A. –9 and 9   B. –10 and 10   C. –6 and 6   D. The equation has no solutions.

Answer 1

`x^2 + 6 = 87 \ \ | -87\\ \\x^2 + 6 -87 = 0 \\ \\ x^2 -81 = 0 \\ \\(x+9)(x-9)=0 \\ \\ x+9 =0 \ \ \vee \ \ x-9 =0 \\ \\ x= -9 \ \ \vee \ \ x= 9 \\ \\\\Answer : \ A.) \ \ -9 \ \ and \ \ 9`



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