Tom thinks of a number. He squares it, adds 3 times the original number and then subtracts 18. The result is 0. What two numbers could Tom have been thinking of?

Formulate the problem algebraically:x2+3x-18=0This is a factorisation problem. To find the solutions, factorise:-Factors of x2 are 1 and 1, so answer will take the form: (x +- ?)(x +- ?)=0-List pairs of factors of 18: (1,18), (2,9), (3,6). -When multiplied by factors of x2, find the factors of 18 that produce the x coeffcient: (3,6). -We now know factorised equation takes the form: (x +- 3)(x +- 6)=0-x coefficient is +3, so correct solution is +6 and -3 (6x+(-3x)=3x).-Factorised equation is (x-3)(x+6)=0-Equation holds when x=-6,3, so the two numbers Tom could have been thinking of are -6 and 3.

Answered by George H. Maths tutor

2831 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

What is the method for factorising the expression 'x^2 + 3x + 2'?


What is the equation of a straight line? Describe what all the terms within the equation do.


State the nth term of the following sequence: 3, 7, 11, 15, 19


Solve the simultaneous equations 3x + y = -4 and 3x - 4y = 6


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2024

Terms & Conditions|Privacy Policy
Cookie Preferences