factorise the following please due in 30min c^2+d^2. e^2/25-f^2/36. and the square root of x-4 thanks no link please​

Step-by-step explanation:

1) c²+d² is not factorable

2) e²/25 - f²/36 = e²/5² - f²/6² = (e/5)² - (f/6)² = (e/5 + f/6) (e/5 - f/6)

3) nothing can be done

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

e.

step-by-step explanation:

because there are always 10 numbers in a phone number.