Begginer Question: Replacing variables with number. - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: Begginer Question: Replacing variables with number. (/thread-7969.html) Begginer Question: Replacing variables with number. - Chris. - 03-17-2017 10:22 PM If i enter Simplify((X^2-7x)(8-x^3)) Calculator returns "-x^5+7x^4+8x^2-56x" How would I tel the calculator to replace all values of x with a number for example -1 I tried Solve(-x^5+7x^4+8x^2-56x,x=-1) And it returned the wrong answer. RE: Begginer Question: Replacing variables with number. - Didier Lachieze - 03-18-2017 12:00 AM You can use subst: subst(-x^5+7*x^4+8*x^2-56*x,x=-1) or define a function: f(x):=(x^2-7*x)*(8-x^3) and then enter f(-1) RE: Begginer Question: Replacing variables with number. - Joe Horn - 03-18-2017 04:04 AM Another way: Use the WHERE symbol (looks like "|"; it's the 3rd item in the template box). Your example would be -x^5+7*x^4+8*x^2-56*x|x=-1.