Posted by **mathlab** on Thursday, March 14, 2013 at 7:34pm.

Solve for x in the equation (x − 7)^2 − 4 = (x + 1)^2.

- math -
**Reiny**, Thursday, March 14, 2013 at 7:51pm
(x − 7)^2 − 4 = (x + 1)^2

x^2 - 14x + 49 - 4 = x^2 + 2x + 1

-16x = -44

x = 44/16 = 11/4 or 2.75

- math -
**mathlab**, Thursday, March 14, 2013 at 7:54pm
follow up quesiton

11/4 or 2.75

how do u convert this without using calculator?

- math -
**Reiny**, Thursday, March 14, 2013 at 8:01pm
to divide by 4 in my head,

I take half of my number and then I take another half

(little tricks that old people still know and use)

so half of 11 is 5.5 and half of 5.5 is 2.75

Think of money, half of $5.50

half of $5 is 2.50, and half of 50 cents is 25 cents

what is 2.50 + 25 cents ?

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