00:01
So the question gives me some expressions for p, q, and r, and then it asks me to evaluate 2p minus q plus r.
00:14
All i need to do now is replace p by what p actually equals.
00:19
So p equals 4x cubed plus x minus 2 minus and then i'm going to replace q by what q is actually equal to which is x squared minus 1 and then plus r.
00:38
So i'm going to replace r by what is the value of r, which is 3x minus 5.
00:45
And once i get here, so for this first part, i need to use what we call the distributive property.
00:52
So the two gets distributed to all the three terms within parentheses.
00:57
I'm going to multiply them out.
00:59
So i have 8x cubed plus 2.
01:06
2x minus 4 and in just the same way the negative sign also gets distributed to everything that's inside the parentheses.
01:18
So i've got to make sure that i distribute the negative sign also.
01:22
Now please remember a negative times a negative is negative and a negative times positive is.
01:29
A negative times negative is positive and a negative times positive is negative.
01:34
So every sign gets changed...