Step-by-step explanation:
Step 1: After adding 875 to both sides of the original equation, you get
[tex]x^2+10x+\text{ ----- }=875[/tex]
Step 2: b is the coefficient of the x term, so b = 10. Divide in half (always half for completing the square!).
[tex]\frac{10}{2}=5[/tex]
Square that result to get 25. That's c, the amount to add to both sides of the equation.
Step 3: Adding c to both sides produces
[tex]x^2+10x+25=875+25[/tex]
Step 4: The result of Step 3 is [tex]x^2+10x+25=900[/tex], and the left side factors as a perfect square.
[tex](x+5)^2=900[/tex]
Step 5: After taking square roots of both sides, you get
[tex]x+5=\pm 30[/tex] which represents "two equations in one."
Separate them.
[tex]x+5=30 \text{ or } x+5 =-30\\x=25 \text{ or } x=-35[/tex]
