Solve the simultaneous equations x^2 +8y=20 and y=x+4

To begin you must substitute the value of y provided into the first equation. The would change the equation into the following form:x^2+8(x+4)=20. Now expand the bracket so that the equation becomes:x^2+8x+32=20.Now subtract 20 from both sides to form a quadratic equationx^2+8x+12=0.Factorise the equation into (x+6)(x+2)=0 As 6 and 2 multiply to make 12 and add together to make 8. You can find all the factor pairs of twelve and check them to see if the add to make 8 in an exam to make sure there are no other possible answers. Since one of the two brackets must be equal to 0 x must be either -6 or -2 for this question. Substitute one of the values of x into the second equation provided.y=-6+4=-2. Therefore when x=-6, y=-2Repeat with the other value of x.y=-2+4=2. Therefore when x=-2, y-=2. In an exam remember to show your working as even if you come to the wrong answer you may still score some method marks which may boost your overall grade.

AM
Answered by Anthony M. Maths tutor

2797 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

1. Find the value of the missing edge to 2 decimal places 2. Find the angle θ to 2 decimal places


A square, with sides of length x cm, is inside a circle. Each vertex of the square is on the circumference of the circle. The area of the circle is 49 cm^2. Work out the value of x. Give your answer correct to 3 significant figures.


Solve the simultaneous equations y = x + 3 and y = x^2 + 3x


A circle with diameter 6cm is cut from a square with side length 7cm. What is the remaining area of the square? You may assume pi = 3 for this question.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning