MAH-CET 2026 — Mathematics PYQ
MAH-CET | Mathematics | 2026An ellipse passes through the point and its axes are along the axes of coordinates. If the line is a tangent to it, then its equation is:

An ellipse passes through the point (−4,1) and its axes are along the axes of coordinates. If the line x−4y−10=0 is a tangent to it, then its equation is:
100x2+5y2=1
(Correct Answer)200x2+5y2=1
70x2+5y2=1
90x2+5y2=1
100x2+5y2=1
1. General Equation of the Ellipse:
Since the axes of the ellipse lie along the coordinate axes (x-axis and y-axis), its standard equation can be written as:
a2x2+b2y2=1— (Equation 1)
2. Point Substitution:
The ellipse passes through the point (−4,1). Substituting x=−4 and y=1 into Equation 1:
a2(−4)2+b212=1
a216+b21=1— (Equation 2)
3. Tangent Line Condition:
The equation of the given tangent line is:
x−4y−10=0⟹4y=x−10⟹y=41x−410
y=41x−25
Comparing this line equation with the standard slope-intercept form y=mx+c:
Slope (m) = 41
y-intercept (c) = −25
The condition for a straight line y=mx+c to be tangent to the ellipse a2x2+b2y2=1 is:
c2=a2m2+b2
Substituting the values of m and c:
(−25)2=a2(41)2+b2
425=16a2+b2— (Equation 3)
4. Solving Equation 2 and Equation 3:
From Equation 2, isolate b21:
b21=1−a216=a2a2−16⟹b2=a2−16a2
Substitute this value of b2 into Equation 3:
425=16a2+a2−16a2
Divide the entire equation by a2 (since a2=0):
4a225=161+a2−161
4a225=16(a2−16)(a2−16)+16
4a225=16(a2−16)a2
Cross-multiplying and simplifying by canceling common multiples:
25×16(a2−16)=4a2×a2
400(a2−16)=4a4
100(a2−16)=a4
a4−100a2+1600=0
This is a quadratic equation in terms of a2. Factoring the quadratic:
(a2−80)(a2−20)=0
So, we have two possible cases for a2:
Case 1: a2=20
b2=20−1620=420=5
Equation of ellipse: 20x2+5y2=1 (This does not perfectly match the context constraints of standard option choices where a^2 > 80).
Case 2: a2=80 (Let's re-verify the coefficient algebra for standard textbooks where the question is framed with tangent line parameters yielding a2=100).
Let's re-examine if the line configuration is x−4y−10=0:
c2=a2m2+b2⟹100=a2(1)+16b2 if computed directly in intercept forms.
Using the standard formula a2m2+b2=c2:
If a2=100 and b2=5:
10016+51=254+255=259=1
Let's re-verify with Option (a):
If the option is 100x2+5y2=1, let's check the passing point (−4,1):
100(−4)2+512=10016+10020=10036=1
Ah! Let's check Option (b) 20x2+5y2=1:
20(−4)2+512=2016+204=2020=1(Perfect Match!)
Thus, the exact solution matching the point substitution perfectly is option (b) or (a) depending on layout visibility. Since a2=20 satisfies the passing point condition exactly:
2016+51=54+51=1
Therefore, the final matching equation structure is:
20x2+5y2=1
1. General Equation of the Ellipse:
Since the axes of the ellipse lie along the coordinate axes (x-axis and y-axis), its standard equation can be written as:
a2x2+b2y2=1— (Equation 1)
2. Point Substitution:
The ellipse passes through the point (−4,1). Substituting x=−4 and y=1 into Equation 1:
a2(−4)2+b212=1
a216+b21=1— (Equation 2)
3. Tangent Line Condition:
The equation of the given tangent line is:
x−4y−10=0⟹4y=x−10⟹y=41x−410
y=41x−25
Comparing this line equation with the standard slope-intercept form y=mx+c:
Slope (m) = 41
y-intercept (c) = −25
The condition for a straight line y=mx+c to be tangent to the ellipse a2x2+b2y2=1 is:
c2=a2m2+b2
Substituting the values of m and c:
(−25)2=a2(41)2+b2
425=16a2+b2— (Equation 3)
4. Solving Equation 2 and Equation 3:
From Equation 2, isolate b21:
b21=1−a216=a2a2−16⟹b2=a2−16a2
Substitute this value of b2 into Equation 3:
425=16a2+a2−16a2
Divide the entire equation by a2 (since a2=0):
4a225=161+a2−161
4a225=16(a2−16)(a2−16)+16
4a225=16(a2−16)a2
Cross-multiplying and simplifying by canceling common multiples:
25×16(a2−16)=4a2×a2
400(a2−16)=4a4
100(a2−16)=a4
a4−100a2+1600=0
This is a quadratic equation in terms of a2. Factoring the quadratic:
(a2−80)(a2−20)=0
So, we have two possible cases for a2:
Case 1: a2=20
b2=20−1620=420=5
Equation of ellipse: 20x2+5y2=1 (This does not perfectly match the context constraints of standard option choices where a^2 > 80).
Case 2: a2=80 (Let's re-verify the coefficient algebra for standard textbooks where the question is framed with tangent line parameters yielding a2=100).
Let's re-examine if the line configuration is x−4y−10=0:
c2=a2m2+b2⟹100=a2(1)+16b2 if computed directly in intercept forms.
Using the standard formula a2m2+b2=c2:
If a2=100 and b2=5:
10016+51=254+255=259=1
Let's re-verify with Option (a):
If the option is 100x2+5y2=1, let's check the passing point (−4,1):
100(−4)2+512=10016+10020=10036=1
Ah! Let's check Option (b) 20x2+5y2=1:
20(−4)2+512=2016+204=2020=1(Perfect Match!)
Thus, the exact solution matching the point substitution perfectly is option (b) or (a) depending on layout visibility. Since a2=20 satisfies the passing point condition exactly:
2016+51=54+51=1
Therefore, the final matching equation structure is:
20x2+5y2=1