Question
Factorise:
$x^2-21 x+90$
$x^2-21 x+90$
✓
Answer
$x^2-21 x+90$
$=x^2-6 x-15 x+90$
$=x(x-6)-15(x-6)$
$=(x-6)(x-15)$
$=x^2-6 x-15 x+90$
$=x(x-6)-15(x-6)$
$=(x-6)(x-15)$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
In the adjoining figure, ABC and ABD are two triangles on the same base AB. If line segment CD is
bisected by AB at O, show that $\text{ar}(\triangle\text{ABC})=\text{ar}(\triangle\text{ABD}).$
→bisected by AB at O, show that $\text{ar}(\triangle\text{ABC})=\text{ar}(\triangle\text{ABD}).$
Factorise:
$x^4-625$
→$x^4-625$
Define the following terms:
Line segment.
Line segment.
Retionalise the denominator of each of the following:$\frac{\sqrt2+\sqrt5}{\sqrt3}$
→Expand:$\Big(\frac{1}{2}\text{a}-\frac{1}{4}\text{b}+2\Big)^2$
→Points D and E are the midpoints of side AB and side AC of ∆ABC respectively. Point F is on ray ED such that ED = DF. Prove that □AFBE is a parallelogram. For this example write ‘given’ and ‘to prove’ and complete the proof.
Given: D and E are the midpoints of side AB and side AC respectively.
ED = DF
To prove: □AFBE is a parallelogram.
In the given figure, ∠PQR = 90°, ∠PQS = 90°, ∠PRQ = α and ∠QPS = θ. Write the following trigonometric ratios.
i. sin α, cos α , tan α
ii. sin θ, cos θ, tan θ
i. sin α, cos α , tan α
ii. sin θ, cos θ, tan θ
$\square \mathrm{PQRS}$ is a parallelogram. $\mathrm{PQ}=3.5, \mathrm{PS}=5.3 \angle \mathrm{Q}=50^{\circ}$ then find the lengths of remaining sides and measures of remaining angles.
→A metallic sphere of radius 10.5cm is melted and thus recast into small cones, each of radius 3.5cm and height 3cm. Find how many cones are obtained.
If each angle of a triangle is less than the sum of the other two, show that the triangle is acute angled.