Easy -1.2 This is a straightforward simultaneous equations question requiring substitution of one linear equation into another and basic algebraic manipulation. It's a standard C1 exercise with no conceptual difficulty—purely mechanical application of a routine technique with minimal steps for 4 marks.
or multiplication to make one pair of coefficients the same; condone one error in either method
simplification to \(ax = b\) or \(ax - b = 0\) form, or equivalent for \(y\)
M1
or appropriate subtraction / addition; condone one error in either method; independent of first M1
\((0.7, 0.1)\) oe or \(x = 0.7, y = 0.1\) oe isw
A2 [4]
A1 each
Question 3 (i)
Answer
Marks
Guidance
25
2
M1 for \(\left(\frac{10}{2}\right)^2\) or \(\left(\frac{1}{0.2}\right)^2\) oe soi; or for \(\frac{1}{0.04}\) oe; ie M1 for one of the two powers used correctly; M0 for just \(\frac{1}{0.4}\) with no other working
[2]
Question 3 (ii)
Answer
Marks
Guidance
\(8a^9\)
3
B2 for 8 or M1 for \(16^{\frac{1}{2}} = 2\) soi; and B1 for \(a^9\); ignore \(\pm\); eg M1 for \(2^3\); M0 for just 2
[3]
substitution to eliminate one variable | M1 | or multiplication to make one pair of coefficients the same; condone one error in either method
simplification to $ax = b$ or $ax - b = 0$ form, or equivalent for $y$ | M1 | or appropriate subtraction / addition; condone one error in either method; independent of first M1
$(0.7, 0.1)$ oe or $x = 0.7, y = 0.1$ oe isw | A2 [4] | A1 each
## Question 3 (i)
25 | 2 | M1 for $\left(\frac{10}{2}\right)^2$ or $\left(\frac{1}{0.2}\right)^2$ oe soi; or for $\frac{1}{0.04}$ oe; ie M1 for one of the two powers used correctly; M0 for just $\frac{1}{0.4}$ with no other working
[2]
## Question 3 (ii)
$8a^9$ | 3 | B2 for 8 or M1 for $16^{\frac{1}{2}} = 2$ soi; and B1 for $a^9$; ignore $\pm$; eg M1 for $2^3$; M0 for just 2
[3]